This app was mentioned in 9 comments, with an average of 1.22 upvotes
I used Resize Me! at one time. Some recommend JPEG Optimizer.
Ive always used this https://play.google.com/store/apps/details?id=com.xnview.XnResizeLite
I use Resize Me!
It's simple and isnt bloated. Resizing and cropping, and thats it.
https://play.google.com/store/apps/details?id=com.xnview.XnResizeLite&hl=en_GB