Jamie Dąbrowiecki

Every installation of Divi adds a set of buttons to the WYSIWYG (TinyMCE) toolbar in the Classic Editor. These are dated, and most users who utilise the Divi Theme Builder or Page Builder will not use these.
This simple plugin removes the following Divi-specific icons from the toolbar:
<ul>
<li>Add ET Learn More Block</li>
<li>Add ET Box</li>
<li>Add ET Button</li>
<li>Add ET Tabs</li>
<li>Add Author Bio</li>
</ul>
This plugin is compatible with all versions of Divi that have the aforementioned buttons in the TinyMCE toolbar – this includes Divi 5.

Toolbar Cleanup for Divi

Removes the Divi-specific buttons that are added to the TinyMCE toolbar in the Classic Editor.

David Klhufek

This simple plugin adds useful buttons to the native WordPress HTML editor (Classic Editor).
Currently adds: 
h1, h2, h3, h4, h5, span, hr, nbsp, mox
The “mox” button adds a nice responsive CSS class which you can use to highlight pictures or other elements in your posts.
Note: This plugin works only with the Classic Editor. It does not support the new Gutenberg (Block Editor).
<h3>Compatibility</h3>
<ul>
<li>Requires the Classic Editor to be active. </li>
<li>Designed specifically for the HTML mode of the editor.</li>
</ul>

Quicktags for WP

This simple plugin adds useful buttons to the native WordPress HTML editor.

Toolbar Cleanup for Divi vs Quicktags for WP