This app was mentioned in 2 comments, with an average of 1.50 upvotes
Thumbzilla. https://play.google.com/store/apps/details?id=com.soapcreative.thumbzilla
That turned out very different from what I expected.
https://play.google.com/store/apps/details?id=com.soapcreative.thumbzilla
Then realized it's a website, not an app.