Does regenerating thumbnails trigger optimization?

I’m using the Shortpixel WP plugin and am needing to regenerate some thumbnail sizes. I’m using the “Regenerate Thumbnails” plugin (https://www.ads-software.com/plugins/regenerate-thumbnails/).

My question is, when thumbnails are regenerated, either via a plugin or the command line (via ‘wp media regenerate’), does Shortpixel re-optimize the thumbnails? If not, is there a way to make it do this?

I’ve tried installing the “Regenerate Thumbnails Advanced” plugin by Shortpixel, but frankly, can’t really understand what it’s doing. Plus, I need to be able to regenerate thumbnails for just one image if necessary.

Hope someone can clarify what happens when thumbs are regenerated.

Thanks,
AJ