How to find theme use site?

I want to know how to get a list of sites that use the selected WP theme?

For an instance Twenty Twenty-One WP theme use site.

There are sites like whatwpthemeisthat.com/ where you can detect what theme choosen site using, i doubd there is some list of sites with choosen theme, but you can contact owners of these sites, maybe they are storint data of each site?