Andrei Zhitkov

Defining your default canonical arbitrary is most useful for those unfortunate souls who have their site URLs in punycode. This plugin allows setting a default custom URL to be used as canonical. It is designed to work with Yoast SEO only. The individual settings are still available and can be edited as before. Since it is dependent on presence of Yoast SEO, this plugin will not activate without it. 
The plugin does not add its own settings page, It uses WordPress Settings -> General. Look for it at the bottom of that page.
<h3>Technical Details</h3>
Supported versions: 
WordPress 4.x 
WordPress 5.x 
WordPress 6.x 
Yoast SEO 6.x-20.x

Custom canonical URL for Yoast SEO

This plugin allows setting a default custom URL to be used as canonical. It is designed to work with Yoast SEO only.

Andon Ivanov

OZ Canonical is a plugin which helps you to edit the canonical attribute easily and fast on all of your blog’s pages.

OZ Canonical

OZ Canonical is a plugin which helps you to edit the canonical attribute easily and fast on all of your blog's pages.

Custom canonical URL for Yoast SEO vs OZ Canonical