Editor Filters (Experimental) 
Edit
To modify the behavior of the editor experience, the following Filters are exposed:
editor.PostFeaturedImage.imageSize editor.PostFeaturedImage.imageSize
Used to modify the image size displayed in the Post Featured Image component. It defaults to 'post-thumbnail', and will fail back to the full image size when the specified image size doesn’t exist in the media object. It’s modeled after the admin_post_thumbnail_size filter in the classic editor.
Example:
var withImageSize = function( size, mediaId, postId ) {
return 'large';
};
wp.hooks.addFilter( 'editor.PostFeaturedImage.imageSize', 'my-plugin/with-image-size', withImageSize );
editor.PostPreview.interstitialMarkup editor.PostPreview.interstitialMarkup
Filters the interstitial message shown when generating previews.
Example:
var customPreviewMessage = function() {
return '<b>Post preview is being generated!</b>';
};
wp.hooks.addFilter( 'editor.PostPreview.interstitialMarkup', 'my-plugin/custom-preview-message', customPreviewMessage );
Editor settings Editor settings
block_editor_settings block_editor_settings
This is a PHP filter which is applied before sending settings to the WordPress block editor.
You may find details about this filter on its WordPress Code Reference page.
The filter will send any setting to the initialized Editor, which means any editor setting that is used to configure the editor at initialisation can be filtered by a PHP WordPress plugin before being sent.
Available default editor settings Available default editor settings
richEditingEnabled richEditingEnabled
If it is true the user can edit the content using the visual editor.
It is set by default to the return value of the user_can_richedit function. It checks if the user can access the visual editor and whether it’s supported by the user’s browser.
codeEditingEnabled codeEditingEnabled
Default true. Indicates whether the user can access the code editor in addition to the visual editor.
If set to false the user will not be able to switch between visual and code editor. The option in the settings menu will not be available and the keyboard shortcut for switching editor types will not fire.