Qrzysio

This plugin converts every uploaded JPG or PNG into a WebP image to make your site faster and lighter. It also removes the original file to save space and avoid duplicates, and sets the image alt text automatically from the filename.
<h3>Configuration</h3>
You can set the image quality in Tools → Force WebP. 
Choose your preferred value and save the settings. The new quality will be used for all images uploaded after you change it.

Force WebP

Say goodbye to JPG and PNG – make your site run on fast, modern WebP images.

kristarella

Copy or convert terms between taxonomies.
Taxonomies include categories, tags and any other custom taxonomies that may be present with your active theme and plugins.
This plugin, based on Categories to Tags Converter, allows you to copy (duplicate) or convert (move) terms from one taxonomy to another or to multiple taxonomies, while maintaining associated posts.

Taxonomy Converter

For starters, the plugin has deprecated code and produces errors on PHP7. Looks like the code hasn't really been touched all that much in many, many years.

The biggest problem is that when the terms are converted, the term descriptions are removed.

Doesn't include term descriptions

Copy or convert terms between taxonomies.

Force WebP vs Taxonomy Converter