This free "Classic Editor Addon" plugin makes sure that Gutenberg cannot be activated accidentally.
Lean WP does a great job cleaning up the WordPress backend (Dashboard) and frontend!
Sets WP_DEBUG to true without the need to touch any files.
Hides the Navigation Menu from the Customizer so as not to confuse anyone.
Clean up several unwanted things that the Yoast SEO plugin adds to your WordPress Dashboard.
With the Responsive Content plugin you can easily adjust the length of your content for different devices.