Guahan Web

This plugin gives you the flexibility to add Ajax handling for your comments to keep the page from having to refresh every post. The administration panel will allow you to customize your processing, success and error messages.
Additionally, this plugin gives you the option of setting up the WYSIWYG editor for comment submission as well. The admin panel will give you the option to show/hide various button groups for the editor and only allows basic editing capabilities. If logged in as administrator, you will still receive the full WYSIWYG editor for your commenting.

GuahanWeb AJAX & WYSIWYG Comments

Adds customization for Ajax commenting and allows for enabling of custom WYSIWYG editor.

Andrew Ozz

This plugin is intended for more advanced users that would like to change the default TinyMCE configuration in WordPress. 
It makes it very easy to add, remove or change all TinyMCE settings for the classic editor and for the classic block in the block editor.

Advanced TinyMCE Configuration

Set advanced TinyMCE options for the classic block and classic editor.

GuahanWeb AJAX & WYSIWYG Comments vs Advanced TinyMCE Configuration