Set default alignments in theme.json

[carolinan]

What problem does this address?

In block themes, when alignments are set in the block markup itself, there is no way to change this alignment using style variations.

Example:

<!-- wp:heading {"textAlign":"center","align":"wide","style":{"spacing":{"margin":{"top":"var:preset|spacing|60","bottom":"var:preset|spacing|50"}}}} -->
<h2 class="alignwide has-text-align-center" style="margin-top:var(--wp--preset--spacing--60);margin-bottom:var(--wp--preset--spacing--50)">Mindblown: a blog about philosophy.</h2>
<!-- /wp:heading -->

Because "textAlign":"center" and has-text-align-center is in the markup, it can not be changed by adding a style variation.
If the textAlign: "center" was in theme.json, then blue.json could set it to textAlign: "none" or similar.

What is your proposed solution?

Allow setting default alignments for blocks using theme.json. Then alignments that are consistent with the default, can be removed from the HTML files in block themes.

[mtias]

Duplicate of #30761 ?

[carolinan]

I meant left/right/center alignments.
For example, setting the post title to be centered by default. This was proposed by @critterverse for the style variations in TT3, but it is not possible today.