Nick Leghorn

This plugin adds a section to your Settings menu in the wp-admin section. Through that section you can perform two tasks:
<ul>
<li>A scripted, one-time action updating all of the posts in your blog that do not have a featured image where the script will either try to find a suitable image to use or use one you have provided and configure it for you.</li>
<li>An ongoing, continuous monitoring for posts that do not have a featured image, using the same logic to try and find a suitable featured image and setting that for the post.</li>
</ul>
You can find additional documentation for this plugin on the author’s blog <a href="https://blog.nickleghorn.com/2021/01/25/adding-a-featured-image-to-all-posts-in-wordpress-in-one-easy-click/" title="blog.nickleghorn.com" rel="nofollow ugc">blog.nickleghorn.com</a>
Special thanks to Robert Farago for giving me yet another massive site without any Featured Images to clean up for the impetus to finally make this available.

Featured Image Bulk Set Plugin

This is a plugin designed to do one simple job: programatically add a featured image in WordPress to existing posts. Either images already in the post …

2ByteCode

Tassawer Hussain

All-in-One Utilities is a versatile plugin that allows administrators to streamline their WordPress site by enabling only the necessary features. Reduce site overhead and manage user roles and settings efficiently with these key features.
This plugin consolidates the functionality of several popular plugins into one lightweight package: 
– Default Featured Image 
– Easy Username Updater 
– Multiple Roles 
– Disable Everything
<ol>
<li>
User Multiple Roles: Assign multiple roles to users during creation or editing.
</li>
<li>
Username Updater: Easily update usernames for users via a dedicated action in the Users list table, with optional email notification.
</li>
<li>
Default Featured Image: Choose a fallback featured image in Media Settings that is applied when posts/pages lack one.
</li>
<li>
Disable Unnecessary Features: Toggle off various WordPress features (e.g., author archives, application passwords, adjacent posts, embeds, emojis) to streamline and speed up your site.
</li>
</ol>
<h3>License</h3>
This plugin is licensed under the GPLv2 or later.

All-in-One Utilities

A must use plugin for any WordPress site with necessary features.

Featured Image Bulk Set Plugin vs All-in-One Utilities