Makoto

Low-Key ToolBar makes the block editor toolbar less noticeable and improve block editor UX.
I think block editor toolbar is useful, but too big and too conspicuous and disturbing. 
Sure, top toolbar mode is not disturbing, but is not user-friendly.
This plugin add its own setting sidebar to block editor and You can control scale, opacity, vertical position of the block editor toolbar.
By adjusting these properteis, the toolbar will be less noticeable, and it will improve UX.

Low-Key ToolBar

This plugin makes the block editor toolbar less noticeable and improve block editor UX. You can control Scale, Opacity, Vertical Position of the block …

Michael Dance

This humble plugin adds an option in Settings > General that controls who sees the WP Toolbar when viewing your site.
You can turn the Toolbar on or off per user role.
Note that this controls the public, front-end version of your site. When viewing the dashboard, the toolbar always appears.
How is this different from other plugins that do similar things? It’s smaller, cleaner, and doesn’t add any unnecesary settings pages. It’s also smart enough to hide the Toolbar option on user profiles if that user is already restricted from seeing the toolbar.

Disable Toolbar

Control who sees the WP Toolbar when viewing your site.

Low-Key ToolBar vs Disable Toolbar