diff --git a/.vscode/launch.json b/.vscode/launch.json
index 116f5ef9480..7a5d2c24080 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -15,7 +15,7 @@
 				"--inspect-brk",
 				"${workspaceRoot}/node_modules/.bin/jest",
 				// Optionally specify a single test file to run/debug:
-				"generateClient.test.ts",
+				"AWSAppSyncRealTimeProvider.test.ts",
 				"--runInBand",
 				"--testTimeout",
 				"600000", // 10 min timeout so jest doesn't error while we're stepping through code
diff --git a/packages/api-graphql/__tests__/AWSAppSyncRealTimeProvider.test.ts b/packages/api-graphql/__tests__/AWSAppSyncRealTimeProvider.test.ts
index 4500ce8a566..0675cc0fcaa 100644
--- a/packages/api-graphql/__tests__/AWSAppSyncRealTimeProvider.test.ts
+++ b/packages/api-graphql/__tests__/AWSAppSyncRealTimeProvider.test.ts
@@ -1104,6 +1104,33 @@ describe('AWSAppSyncRealTimeProvider', () => {
 						);
 					});
 
+					test('authenticating with AWS_LAMBDA/custom w/ custom header function that accepts request options', async () => {
+						expect.assertions(2);
+
+						provider
+							.subscribe({
+								appSyncGraphqlEndpoint: 'ws://localhost:8080',
+								authenticationType: 'none',
+								additionalHeaders: async requestOptions => {
+									expect(requestOptions).toEqual(
+										expect.objectContaining({
+											queryString: '',
+											url: 'ws://localhost:8080',
+										})
+									);
+									return { Authorization: 'test' };
+								},
+							})
+							.subscribe({ error: () => {} });
+
+						await fakeWebSocketInterface?.readyForUse;
+
+						expect(loggerSpy).toHaveBeenCalledWith(
+							'DEBUG',
+							'Authenticating with "none"'
+						);
+					});
+
 					test('authenticating with AWS_LAMBDA/custom without Authorization', async () => {
 						expect.assertions(1);
 
diff --git a/packages/api-graphql/__tests__/__snapshots__/generateClient.test.ts.snap b/packages/api-graphql/__tests__/__snapshots__/generateClient.test.ts.snap
index 15e016542db..2cedf31b865 100644
--- a/packages/api-graphql/__tests__/__snapshots__/generateClient.test.ts.snap
+++ b/packages/api-graphql/__tests__/__snapshots__/generateClient.test.ts.snap
@@ -2772,6 +2772,63 @@ exports[`generateClient basic model operations - custom client and request heade
 ]
 `;
 
+exports[`generateClient basic model operations - custom client and request headers can create() - with custom client header functions that pass requestOptions 1`] = `
+[
+  [
+    {
+      "abortController": AbortController {},
+      "options": {
+        "body": {
+          "query": "mutation ($input: CreateTodoInput!) {
+  createTodo(input: $input) {
+    id
+    name
+    description
+    status
+    tags
+    createdAt
+    updatedAt
+    todoMetaId
+    owner
+  }
+}
+",
+          "variables": {
+            "input": {
+              "description": "something something",
+              "name": "some name",
+            },
+          },
+        },
+        "headers": {
+          "X-Api-Key": "FAKE-KEY",
+          "rq-method": "POST",
+          "rq-qs": "mutation ($input: CreateTodoInput!) {
+  createTodo(input: $input) {
+    id
+    name
+    description
+    status
+    tags
+    createdAt
+    updatedAt
+    todoMetaId
+    owner
+  }
+}
+",
+          "rq-url": "https://localhost/graphql",
+          "x-amz-user-agent": "aws-amplify/latest api/latest framework/latest",
+        },
+        "signingServiceInfo": undefined,
+        "withCredentials": undefined,
+      },
+      "url": "https://localhost/graphql",
+    },
+  ],
+]
+`;
+
 exports[`generateClient basic model operations - custom client and request headers can create() - with custom client headers 1`] = `
 [
   [
@@ -2856,6 +2913,63 @@ exports[`generateClient basic model operations - custom client and request heade
 ]
 `;
 
+exports[`generateClient basic model operations - custom client and request headers can create() - with custom request header function that accept requestOptions 1`] = `
+[
+  [
+    {
+      "abortController": AbortController {},
+      "options": {
+        "body": {
+          "query": "mutation ($input: CreateTodoInput!) {
+  createTodo(input: $input) {
+    id
+    name
+    description
+    status
+    tags
+    createdAt
+    updatedAt
+    todoMetaId
+    owner
+  }
+}
+",
+          "variables": {
+            "input": {
+              "description": "something something",
+              "name": "some name",
+            },
+          },
+        },
+        "headers": {
+          "X-Api-Key": "FAKE-KEY",
+          "rq-method": "POST",
+          "rq-qs": "mutation ($input: CreateTodoInput!) {
+  createTodo(input: $input) {
+    id
+    name
+    description
+    status
+    tags
+    createdAt
+    updatedAt
+    todoMetaId
+    owner
+  }
+}
+",
+          "rq-url": "https://localhost/graphql",
+          "x-amz-user-agent": "aws-amplify/latest api/latest framework/latest",
+        },
+        "signingServiceInfo": undefined,
+        "withCredentials": undefined,
+      },
+      "url": "https://localhost/graphql",
+    },
+  ],
+]
+`;
+
 exports[`generateClient basic model operations - custom client and request headers can create() - with custom request headers 1`] = `
 [
   [
diff --git a/packages/api-graphql/__tests__/generateClient.test.ts b/packages/api-graphql/__tests__/generateClient.test.ts
index d445335c94b..9951586e20e 100644
--- a/packages/api-graphql/__tests__/generateClient.test.ts
+++ b/packages/api-graphql/__tests__/generateClient.test.ts
@@ -66,23 +66,23 @@ function makeAppSyncStreams() {
  * replaces fields that are likely to change between calls (or library version revs)
  * with static values. When possible, on the unpredicable portions of these values
  * are replaced.
- * 
+ *
  * ## THIS IS DESTRUCTIVE
- * 
+ *
  * The original `spy.mocks.calls` will be updated *and* returned.
- * 
+ *
  * For example,
- * 
+ *
  * ```plain
  * headers.x-amz-user-agent: "aws-amplify/6.0.5 api/1 framework/0"
  * ```
- * 
+ *
  * Is replaced with:
- * 
+ *
  * ```plain
  * headers.x-amz-user-agent: "aws-amplify/latest api/latest framework/latest"
  * ```
- * 
+ *
  * @param spy The Jest spy
  */
 function normalizePostGraphqlCalls(spy: jest.SpyInstance<any, any>) {
@@ -251,7 +251,7 @@ describe('generateClient', () => {
 				description: 'something something',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -272,7 +272,7 @@ describe('generateClient', () => {
 						...serverManagedFields,
 						name: 'some name',
 						description: 'something something',
-						tags: ['one', 'two', 'three']
+						tags: ['one', 'two', 'three'],
 					},
 				},
 			});
@@ -280,7 +280,7 @@ describe('generateClient', () => {
 			const client = generateClient<Schema>({ amplify: Amplify });
 			const { data } = await client.models.Todo.get({ id: 'asdf' });
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -289,7 +289,7 @@ describe('generateClient', () => {
 					owner: 'wirejobviously',
 					name: 'some name',
 					description: 'something something',
-					tags: ['one', 'two', 'three']
+					tags: ['one', 'two', 'three'],
 				})
 			);
 		});
@@ -315,8 +315,8 @@ describe('generateClient', () => {
 				filter: { name: { contains: 'name' } },
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
-			
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
+
 			expect(data.length).toBe(1);
 			expect(data[0]).toEqual(
 				expect.objectContaining({
@@ -351,7 +351,7 @@ describe('generateClient', () => {
 				nextToken: 'some-token',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can list() with limit', async () => {
@@ -376,7 +376,7 @@ describe('generateClient', () => {
 				limit: 5,
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can update()', async () => {
@@ -397,7 +397,7 @@ describe('generateClient', () => {
 				name: 'some other name',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -427,7 +427,7 @@ describe('generateClient', () => {
 				id: 'some-id',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -590,7 +590,7 @@ describe('generateClient', () => {
 
 			const { data: notes } = await data.notes();
 
-			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 
 			expect(notes!.length).toBe(1);
 			expect(notes![0]).toEqual(
@@ -636,7 +636,7 @@ describe('generateClient', () => {
 
 			const { data: notes } = await data.notes({ nextToken: 'some-token' });
 
-			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 
 			expect(notes!.length).toBe(1);
 			expect(notes![0]).toEqual(
@@ -682,7 +682,7 @@ describe('generateClient', () => {
 
 			const { data: notes } = await data.notes({ limit: 5 });
 
-			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 
 			expect(notes!.length).toBe(1);
 			expect(notes![0]).toEqual(
@@ -725,7 +725,7 @@ describe('generateClient', () => {
 
 			const { data: todo } = await data.todo();
 
-			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 
 			expect(todo).toEqual(
 				expect.objectContaining({
@@ -766,7 +766,7 @@ describe('generateClient', () => {
 
 			const { data: todo } = await data.meta();
 
-			expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 
 			expect(todo).toEqual(
 				expect.objectContaining({
@@ -823,7 +823,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can get()', async () => {
@@ -841,7 +841,7 @@ describe('generateClient', () => {
 			const client = generateClient<Schema>({ amplify: Amplify });
 			await client.models.Todo.get({ id: 'asdf' }, { authMode: 'userPool' });
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can list()', async () => {
@@ -866,7 +866,7 @@ describe('generateClient', () => {
 				authMode: 'userPool',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can update()', async () => {
@@ -890,7 +890,7 @@ describe('generateClient', () => {
 				{ authMode: 'userPool' }
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can delete()', async () => {
@@ -913,7 +913,7 @@ describe('generateClient', () => {
 				{ authMode: 'userPool' }
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can subscribe to onCreate()', done => {
@@ -1064,7 +1064,7 @@ describe('generateClient', () => {
 
 				await data.notes();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -1102,7 +1102,7 @@ describe('generateClient', () => {
 
 				await data.todo();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -1139,7 +1139,7 @@ describe('generateClient', () => {
 
 				await data.meta();
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 
@@ -1180,7 +1180,7 @@ describe('generateClient', () => {
 
 				await data.notes({ authMode: 'apiKey' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -1218,7 +1218,7 @@ describe('generateClient', () => {
 
 				await data.todo({ authMode: 'apiKey' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -1255,7 +1255,7 @@ describe('generateClient', () => {
 
 				await data.meta({ authMode: 'apiKey' });
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 	});
@@ -1306,7 +1306,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can get()', async () => {
@@ -1327,7 +1327,7 @@ describe('generateClient', () => {
 				{ authMode: 'lambda', authToken: 'some-token' }
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can list()', async () => {
@@ -1353,7 +1353,7 @@ describe('generateClient', () => {
 				authToken: 'some-token',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can update()', async () => {
@@ -1377,7 +1377,7 @@ describe('generateClient', () => {
 				{ authMode: 'lambda', authToken: 'some-token' }
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can delete()', async () => {
@@ -1400,7 +1400,7 @@ describe('generateClient', () => {
 				{ authMode: 'lambda', authToken: 'some-token' }
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can subscribe to onCreate()', done => {
@@ -1554,7 +1554,7 @@ describe('generateClient', () => {
 
 				await data.notes();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -1593,7 +1593,7 @@ describe('generateClient', () => {
 
 				await data.todo();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -1631,7 +1631,7 @@ describe('generateClient', () => {
 
 				await data.meta();
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 
@@ -1672,7 +1672,7 @@ describe('generateClient', () => {
 
 				await data.notes({ authMode: 'lambda', authToken: 'some-token' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -1710,7 +1710,7 @@ describe('generateClient', () => {
 
 				await data.todo({ authMode: 'lambda', authToken: 'some-token' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -1747,7 +1747,7 @@ describe('generateClient', () => {
 
 				await data.meta({ authMode: 'lambda', authToken: 'some-token' });
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 	});
@@ -1795,7 +1795,7 @@ describe('generateClient', () => {
 				description: 'something something',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can get()', async () => {
@@ -1816,7 +1816,7 @@ describe('generateClient', () => {
 			});
 			await client.models.Todo.get({ id: 'asdf' });
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can list()', async () => {
@@ -1843,7 +1843,7 @@ describe('generateClient', () => {
 				filter: { name: { contains: 'name' } },
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can update()', async () => {
@@ -1867,7 +1867,7 @@ describe('generateClient', () => {
 				name: 'some other name',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can delete()', async () => {
@@ -1890,7 +1890,7 @@ describe('generateClient', () => {
 				id: 'some-id',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can subscribe to onCreate()', done => {
@@ -2044,7 +2044,7 @@ describe('generateClient', () => {
 
 				await data.notes();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -2080,7 +2080,7 @@ describe('generateClient', () => {
 
 				await data.todo();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -2115,7 +2115,7 @@ describe('generateClient', () => {
 
 				await data.meta();
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 
@@ -2156,7 +2156,7 @@ describe('generateClient', () => {
 
 				await data.notes({ authMode: 'apiKey' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -2192,7 +2192,7 @@ describe('generateClient', () => {
 
 				await data.todo({ authMode: 'apiKey' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -2227,7 +2227,7 @@ describe('generateClient', () => {
 
 				await data.meta({ authMode: 'apiKey' });
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 	});
@@ -2276,7 +2276,7 @@ describe('generateClient', () => {
 				description: 'something something',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can get()', async () => {
@@ -2298,7 +2298,7 @@ describe('generateClient', () => {
 			});
 			await client.models.Todo.get({ id: 'asdf' });
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can list()', async () => {
@@ -2326,7 +2326,7 @@ describe('generateClient', () => {
 				filter: { name: { contains: 'name' } },
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can update()', async () => {
@@ -2351,7 +2351,7 @@ describe('generateClient', () => {
 				name: 'some other name',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can delete()', async () => {
@@ -2375,7 +2375,7 @@ describe('generateClient', () => {
 				id: 'some-id',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can subscribe to onCreate()', done => {
@@ -2533,7 +2533,7 @@ describe('generateClient', () => {
 
 				await data.notes();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -2570,7 +2570,7 @@ describe('generateClient', () => {
 
 				await data.todo();
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -2606,7 +2606,7 @@ describe('generateClient', () => {
 
 				await data.meta();
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 
@@ -2647,7 +2647,7 @@ describe('generateClient', () => {
 
 				await data.notes({ authMode: 'lambda', authToken: 'some-token' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @belongsTo', async () => {
@@ -2683,7 +2683,7 @@ describe('generateClient', () => {
 
 				await data.todo({ authMode: 'lambda', authToken: 'some-token' });
 
-				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildNotesSpy)).toMatchSnapshot();
 			});
 
 			test('can lazy load @hasOne', async () => {
@@ -2718,7 +2718,7 @@ describe('generateClient', () => {
 
 				await data.meta({ authMode: 'lambda', authToken: 'some-token' });
 
-				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot()
+				expect(normalizePostGraphqlCalls(getChildMetaSpy)).toMatchSnapshot();
 			});
 		});
 	});
@@ -2758,7 +2758,7 @@ describe('generateClient', () => {
 				description: 'something something',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -2795,7 +2795,46 @@ describe('generateClient', () => {
 				description: 'something something',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
+
+			expect(data).toEqual(
+				expect.objectContaining({
+					__typename: 'Todo',
+					id: 'some-id',
+					owner: 'wirejobviously',
+					name: 'some name',
+					description: 'something something',
+				})
+			);
+		});
+
+		test('can create() - with custom client header functions that pass requestOptions', async () => {
+			const spy = mockApiResponse({
+				data: {
+					createTodo: {
+						__typename: 'Todo',
+						...serverManagedFields,
+						name: 'some name',
+						description: 'something something',
+					},
+				},
+			});
+
+			const client = generateClient<Schema>({
+				amplify: Amplify,
+				headers: async requestOptions => ({
+					'rq-url': requestOptions?.url || 'should-not-be-present',
+					'rq-qs': requestOptions?.queryString || 'should-not-be-present',
+					'rq-method': requestOptions?.method || 'should-not-be-present',
+				}),
+			});
+
+			const { data } = await client.models.Todo.create({
+				name: 'some name',
+				description: 'something something',
+			});
+
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -2839,7 +2878,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			// Request headers should overwrite client headers:
 			expect(spy).toHaveBeenCalledWith(
@@ -2894,7 +2933,53 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
+
+			expect(data).toEqual(
+				expect.objectContaining({
+					__typename: 'Todo',
+					id: 'some-id',
+					owner: 'wirejobviously',
+					name: 'some name',
+					description: 'something something',
+				})
+			);
+		});
+
+		test('can create() - with custom request header function that accept requestOptions', async () => {
+			const spy = mockApiResponse({
+				data: {
+					createTodo: {
+						__typename: 'Todo',
+						...serverManagedFields,
+						name: 'some name',
+						description: 'something something',
+					},
+				},
+			});
+
+			const client = generateClient<Schema>({
+				amplify: Amplify,
+				headers: {
+					'client-header': 'should not exist',
+				},
+			});
+
+			const { data } = await client.models.Todo.create(
+				{
+					name: 'some name',
+					description: 'something something',
+				},
+				{
+					headers: async requestOptions => ({
+						'rq-url': requestOptions?.url || 'should-not-be-present',
+						'rq-qs': requestOptions?.queryString || 'should-not-be-present',
+						'rq-method': requestOptions?.method || 'should-not-be-present',
+					}),
+				}
+			);
+
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -2927,7 +3012,7 @@ describe('generateClient', () => {
 			});
 			const { data } = await client.models.Todo.get({ id: 'asdf' });
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -2967,7 +3052,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3006,7 +3091,7 @@ describe('generateClient', () => {
 				filter: { name: { contains: 'name' } },
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data.length).toBe(1);
 			expect(data[0]).toEqual(
@@ -3049,7 +3134,7 @@ describe('generateClient', () => {
 				},
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(spy).toHaveBeenCalledWith(
 				expect.objectContaining({
@@ -3097,7 +3182,7 @@ describe('generateClient', () => {
 				name: 'some other name',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3140,7 +3225,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3175,7 +3260,7 @@ describe('generateClient', () => {
 				id: 'some-id',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('can delete() - with custom request headers', async () => {
@@ -3207,7 +3292,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3313,6 +3398,50 @@ describe('generateClient', () => {
 			});
 		});
 
+		test('can subscribe to onCreate() - with a custom header function that accepts requestOptions', done => {
+			const noteToSend = {
+				__typename: 'Note',
+				...serverManagedFields,
+				body: 'a very good note',
+			};
+
+			const graphqlMessage = {
+				data: {
+					onCreateNote: noteToSend,
+				},
+			};
+
+			const graphqlVariables = {
+				filter: {
+					body: { contains: 'good note' },
+				},
+			};
+
+			const client = generateClient<Schema>({ amplify: Amplify });
+
+			const spy = jest.fn(() => from([graphqlMessage]));
+			(raw.GraphQLAPI as any).appSyncRealTime = { subscribe: spy };
+
+			client.models.Note.onCreate({
+				filter: graphqlVariables.filter,
+				headers: async requestOptions => ({
+					'rq-url': requestOptions?.url || 'should-not-be-present',
+					'rq-qs': requestOptions?.queryString || 'should-not-be-present',
+					'rq-method': requestOptions?.method || 'should-not-be-present',
+				}),
+			}).subscribe({
+				next(value) {
+					expectSubWithHeadersFn(spy, 'onCreateNote', graphqlVariables);
+					expect(value).toEqual(expect.objectContaining(noteToSend));
+					done();
+				},
+				error(error) {
+					expect(error).toBeUndefined();
+					done('bad news!');
+				},
+			});
+		});
+
 		test('can subscribe to onUpdate()', done => {
 			const noteToSend = {
 				__typename: 'Note',
@@ -3451,7 +3580,7 @@ describe('generateClient', () => {
 				description: 'something something',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3488,7 +3617,7 @@ describe('generateClient', () => {
 				description: 'something something',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3529,7 +3658,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3562,7 +3691,7 @@ describe('generateClient', () => {
 			});
 			const { data } = await client.models.Todo.get({ id: 'asdf' });
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3602,7 +3731,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3641,7 +3770,7 @@ describe('generateClient', () => {
 				filter: { name: { contains: 'name' } },
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data.length).toBe(1);
 			expect(data[0]).toEqual(
@@ -3684,7 +3813,7 @@ describe('generateClient', () => {
 				},
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(spy).toHaveBeenCalledWith(
 				expect.objectContaining({
@@ -3732,7 +3861,7 @@ describe('generateClient', () => {
 				name: 'some other name',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3775,7 +3904,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3810,7 +3939,7 @@ describe('generateClient', () => {
 				id: 'some-id',
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -3852,7 +3981,7 @@ describe('generateClient', () => {
 				}
 			);
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 			expect(data).toEqual(
 				expect.objectContaining({
@@ -4126,7 +4255,7 @@ describe('generateClient', () => {
 							}),
 						]);
 
-						expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+						expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 
 						done();
 					}
@@ -4806,7 +4935,7 @@ describe('generateClient', () => {
 				query: `query { listTodos { __typename id owner createdAt updatedAt name description } }`,
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 	});
 
@@ -4849,7 +4978,7 @@ describe('generateClient', () => {
 				query: `query { listTodos { __typename id owner createdAt updatedAt name description } }`,
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 
 		test('client auth override query - lambda', async () => {
@@ -4878,7 +5007,7 @@ describe('generateClient', () => {
 				query: `query { listTodos { __typename id owner createdAt updatedAt name description } }`,
 			});
 
-			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot()
+			expect(normalizePostGraphqlCalls(spy)).toMatchSnapshot();
 		});
 	});
 });
diff --git a/packages/api-graphql/package.json b/packages/api-graphql/package.json
index bc0884f65c3..8febfc6b226 100644
--- a/packages/api-graphql/package.json
+++ b/packages/api-graphql/package.json
@@ -72,7 +72,7 @@
 	},
 	"homepage": "https://aws-amplify.github.io/",
 	"devDependencies": {
-		"@aws-amplify/data-schema": "^0.12.9",
+		"@aws-amplify/data-schema": "^0.12.11",
 		"@rollup/plugin-typescript": "11.1.5",
 		"rollup": "3.29.4",
 		"typescript": "5.0.2"
@@ -87,7 +87,7 @@
 	"dependencies": {
 		"@aws-amplify/api-rest": "4.0.7",
 		"@aws-amplify/core": "6.0.7",
-		"@aws-amplify/data-schema-types": "^0.6.6",
+		"@aws-amplify/data-schema-types": "^0.6.10",
 		"@aws-sdk/types": "3.387.0",
 		"graphql": "15.8.0",
 		"rxjs": "^7.8.1",
diff --git a/packages/api-graphql/src/Providers/AWSAppSyncRealTimeProvider/index.ts b/packages/api-graphql/src/Providers/AWSAppSyncRealTimeProvider/index.ts
index a8fb82a05ce..f4d5fdb8a4f 100644
--- a/packages/api-graphql/src/Providers/AWSAppSyncRealTimeProvider/index.ts
+++ b/packages/api-graphql/src/Providers/AWSAppSyncRealTimeProvider/index.ts
@@ -50,6 +50,7 @@ import {
 	ReconnectEvent,
 	ReconnectionMonitor,
 } from '../../utils/ReconnectionMonitor';
+import { CustomHeaders, RequestOptions } from '@aws-amplify/data-schema-types';
 
 const logger = new ConsoleLogger('AWSAppSyncRealTimeProvider');
 
@@ -98,9 +99,7 @@ export interface AWSAppSyncRealTimeProviderOptions {
 	apiKey?: string;
 	region?: string;
 	libraryConfigHeaders?: () => {} | (() => Promise<{}>);
-	additionalHeaders?:
-		| Record<string, string>
-		| (() => Promise<Record<string, string>>);
+	additionalHeaders?: CustomHeaders;
 	additionalCustomHeaders?: Record<string, string>;
 	authToken?: string;
 }
@@ -323,7 +322,11 @@ export class AWSAppSyncRealTimeProvider {
 		let additionalCustomHeaders: Record<string, string> = {};
 
 		if (typeof additionalHeaders === 'function') {
-			additionalCustomHeaders = await additionalHeaders();
+			const requestOptions: RequestOptions = {
+				url: appSyncGraphqlEndpoint || '',
+				queryString: query || '',
+			};
+			additionalCustomHeaders = await additionalHeaders(requestOptions);
 		} else {
 			additionalCustomHeaders = additionalHeaders;
 		}
diff --git a/packages/api-graphql/src/internals/InternalGraphQLAPI.ts b/packages/api-graphql/src/internals/InternalGraphQLAPI.ts
index c306fb63e09..41dab97903c 100644
--- a/packages/api-graphql/src/internals/InternalGraphQLAPI.ts
+++ b/packages/api-graphql/src/internals/InternalGraphQLAPI.ts
@@ -29,7 +29,7 @@ import {
 	updateRequestToBeCancellable,
 } from '@aws-amplify/api-rest/internals';
 import { AWSAppSyncRealTimeProvider } from '../Providers/AWSAppSyncRealTimeProvider';
-import { CustomHeaders } from '@aws-amplify/data-schema-types';
+import { CustomHeaders, RequestOptions } from '@aws-amplify/data-schema-types';
 import { resolveConfig, resolveLibraryOptions } from '../utils';
 import { repackageUnauthError } from '../utils/errors/repackageAuthError';
 
@@ -260,7 +260,15 @@ export class InternalGraphQLAPIClass {
 		let additionalCustomHeaders: Record<string, string>;
 
 		if (typeof additionalHeaders === 'function') {
-			additionalCustomHeaders = await additionalHeaders();
+			const requestOptions: RequestOptions = {
+				method: 'POST',
+				url: new AmplifyUrl(
+					customEndpoint || appSyncGraphqlEndpoint || ''
+				).toString(),
+				queryString: print(query as DocumentNode),
+			};
+
+			additionalCustomHeaders = await additionalHeaders(requestOptions);
 		} else {
 			additionalCustomHeaders = additionalHeaders;
 		}
@@ -351,6 +359,7 @@ export class InternalGraphQLAPIClass {
 		}
 
 		let response: any;
+
 		try {
 			const { body: responseBody } = await this._api.post({
 				url: new AmplifyUrl(endpoint),
diff --git a/yarn.lock b/yarn.lock
index bc07301cf3d..ee390b9f359 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -10,17 +10,17 @@
     "@jridgewell/gen-mapping" "^0.3.0"
     "@jridgewell/trace-mapping" "^0.3.9"
 
-"@aws-amplify/data-schema-types@*", "@aws-amplify/data-schema-types@^0.6.6":
-  version "0.6.7"
-  resolved "https://registry.yarnpkg.com/@aws-amplify/data-schema-types/-/data-schema-types-0.6.7.tgz#4bf14682fe0d7174e7ef9f2c9bb3b84310b171e0"
-  integrity sha512-JmY1R/tuhjj/rQWGUrDR6o67K+7XFHucMVO0F4XIS2jJgOb44/J6sV9Yq9NYPVU0eMFB1Iv5YcZQlS2lGRNdqA==
+"@aws-amplify/data-schema-types@*", "@aws-amplify/data-schema-types@^0.6.10":
+  version "0.6.10"
+  resolved "https://registry.yarnpkg.com/@aws-amplify/data-schema-types/-/data-schema-types-0.6.10.tgz#e208e57dd2e7de0b9d479d19c1d8459b578df506"
+  integrity sha512-o893k1tNJ0iR9w9Q/jymhSQZmgNdH/L5tz+RXyWcQO+qgN3XhGaayqjYKcQ22XkB1pBgGkXtRLO6Jg74KriBWg==
   dependencies:
     rxjs "^7.8.1"
 
-"@aws-amplify/data-schema@^0.12.9":
-  version "0.12.9"
-  resolved "https://registry.yarnpkg.com/@aws-amplify/data-schema/-/data-schema-0.12.9.tgz#89c01c93ab0f0442529dbf20c927cbc969004d28"
-  integrity sha512-S0uN3ZncODzMpDijWfT5uHoytY65KTob/m9N6ltsGsk7h+1+alNkA/PAEya9JWhzIU8gFemW9F/8s9X9S/Nweg==
+"@aws-amplify/data-schema@^0.12.11":
+  version "0.12.11"
+  resolved "https://registry.yarnpkg.com/@aws-amplify/data-schema/-/data-schema-0.12.11.tgz#bc43ada620a2b7311c2523891f96a0bc66ca50c3"
+  integrity sha512-wc7bHMrmw1+gFcY36BaZsPd08vJisfCZjjYzuXREitMHmy97HYbvva22nPbDUciQWTk+87InYflYoS5NJnKspg==
   dependencies:
     "@aws-amplify/data-schema-types" "*"