shooflydesign

This plugin can override the Authors metabox on the post add/edit screen, letting users who can edit other people’s posts, reassign a post to others user on the site.
This is especially useful in situations where you’ve created custom user roles that WordPress doesn’t recognize as Authors. If you want to allow your content editors and administrators to assign new or existing content to anyone, you’ll (hopefully) like this plugin very much indeed.
On WordPress 5.0, the metabox will appear below the main block editor (see screenshot). I will be supporting updates to the Status & Visibility box as soon as possible.
I’m not sure how far back this plugin will work, I’m saying it requires 3.5 or greater — it was originally developed using WordPress 4.1.
(Inspired by <a href="https://core.trac.wordpress.org/ticket/18645" rel="nofollow ugc">this trac ticket</a>)

Better Author Metabox

Lets you safely override the built-in Author metabox with one that includes more users.

_rg_

Let use diferent themes installed for each user role actived.
You can set which theme will be use visible for “administrator” role while logged, or for “editor”, or any other role created. Also, you can set which theme will be visible for rest of visitors, that´s rest of people that are not wp users, just visitors.
It´s very easy, just install it, go to Development Themes Options page, choose your roles/themes and save.
You can use this plugin for things like:
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Put your site under maintenance using some other alternative theme for your site, but let the administrator or any other user role be able to see and work a new theme, let´s say an update.
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You can test some new theme while rest of visitors still see the current one.
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In fact, you can show a theme for any user role that is actived, default ones, or any other role created by some other plugin. Let´s say one of those role managers available. I´ve tested, and works.
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You can also turn Off the plugin, in order to use the actived theme for all users and visitors.

Development Theme

Let use diferent themes installed for each user role actived.

Better Author Metabox vs Development Theme