Igor Benic

Multisite Featured Image changes the box of the featured image for all sites. It can be used also in a single instance of WordPress and not a MU installation.
This plugin changes the box in the way that the default pop-up is replaced with the classic Media Uploader where you can choose images. Images From URL do work.
For a greater Multisite experience you can combine this plugin with the <a href="https://wordpress.org/plugins/network-shared-media/" rel="ugc">Network Shared Media plugin</a> and have a complete Media Sharing site.
Read about it on this <a href="http://siderrz.com/wordpress-multisite-shared-featured-image/" rel="nofollow ugc">article</a>.
<h4>Features</h4>
<ul>
<li>Using WordPress Media Uploader to set Featured Image</li>
<li>You can set an image from URL</li>
<li>Images from URL will be downloaded into the WordPress Media and it can be used for anything else inside WordPress</li>
<li>Downloaded images are saved in every registered image size </li>
<li>You can set the Main site on which you will download the images in a MU installation</li>
</ul>

Multisite Featured Image

Multisite Featured Image changes the box of the featured image so that you can use the classic Media Uploader also with Network Shared Media.

Hugh Lashbrooke

Sick of adding a image to your post content then also setting it as the featured image in a separate action? Of course you are!
This plugin solves this problem by adding a new button alongside the “Insert into post” button in the media manager modal. When clicked, this button will insert your selected media and then, if you have selected an image, set that image as the post’s featured image.
It is possible to select multiple media items to insert, so this plugin will set the last image in the selected set as the featured image. The button will appear in the media manager modal for all post types.
This plugin works with WordPress 5.0+, but it will only work with Classic block or in the Classic Editor. It does not currently work with the Image block (or any other similar ones).
Want to contribute? <a href="https://github.com/hlashbrooke/Instant-Featured-Image" rel="nofollow ugc">Fork the GitHub repository</a>.
Got some great ideas? <a href="https://wordpress.org/support/plugin/instant-featured-image" rel="ugc">Post on the support forum</a>.

Instant Featured Image

Set an image as the featured image at the same time as you insert it into the post content.

Multisite Featured Image vs Instant Featured Image