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.

Informatiza

Sutolix

Automatically convert all images (png and jpg) sent to the WordPress library to webp.
ATTENTION: The original images are not kept, when sending an image it will be as if you had sent a webp from the beginning.
Features include:
<ul>
<li>Set conversion quality.</li>
<li>Set the maximum width/height of images. If an image exceeds the defined value in height or width, the image will be resized to the defined maximum.</li>
<li>Ignore images that have a certain name in the file name</li>
</ul>

Webp Transformer

Convert images from library to webp and resize them during upload

Force WebP vs Webp Transformer