advance text editor

Currently, it’s not built-in but I see that it is a possibility in CKEditor, but you would have to load the plugin manually: https://ckeditor.com/cke4/addon/markdown

There is a guide on how to do this available here:
https://h5p.org/adding-text-editor-buttons

You can probably skip the first part about adding support for custom tags as you probably won’t need this and just add the JS to load the plugin.

There is an example plugin you can use as a template to see how to hook into the actions you’ll need:
https://github.com/h5p/h5pmods-wordpress-plugin/blob/master/h5pmods.php