Add two accessible font sizes to Reader display settings

[kean]

Description

Fixes CMM-980: Reader: add larger font sizes in "Reader Preferences".

Before

After

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Configuration	Release-Alpha
	Build Number	29915
	Version	PR #25013
	Bundle ID	com.jetpack.alpha
	Commit	96594de
	Installation URL	7aa325rfv2hi8

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Configuration	Release-Alpha
	Build Number	29915
	Version	PR #25013
	Bundle ID	org.wordpress.alpha
	Commit	96594de
	Installation URL	1cffdise6rnqo

Automatticians: You can use our internal self-serve MC tool to give yourself access to those builds if needed.