
Custom HTML Block Extension extends “Custom HTML block” to evolve into an advanced code editor.

Features
Various color themes

There are 50 different color themes to choose from, and you can select the one that best suits your taste.
Faster coding with Emmet

Emmet allows you to type shortcuts that are then expanded into full pieces of code. Type less, saving both keystrokes.
High customizability
More support

Supports the classic editor, the theme/plugin editor, import/export editor settings, and change indentation.
Note
This plugin will not work on the “Block Template” editor, which is a new feature in WordPress 5.8.
Add custom fonts
You can use your own favorite fonts in addition to the default fonts.
Please see this document.