Zach, try this:
https://wordpress.org/plugins/auto-post-thumbnail/ (the PRO version is decent and i have it. I've never tried the freeone, but it can probably do what you need.)
The pro version is here and only 14 dollars:
https://codecanyon.net/item/auto-pos...il-pro/4322624
This one can significantly improve the default quality of WordPress thumbs significantly.
https://wordpress.org/plugins/imagemagick-engine/
Note, when regenerating images, it can be a resource hog and can also be a little time consuming depending on how many images you need to re-generate.