Is it possible to control dimensions of cropping an image?
Depending on your needs you might resize all images first, then specify the crop and potentially resize again after if needed. It's really up to your workflow which operation needs to happen in which order.



Photos manually (which also has a very nice square crop tool and can export and re-sample the image if needed). The next step would be to have  automator or AppleScript control Photos (or your editor of choice) to make entering specific dimensions easier. If you don't mind shell scripting, the tool I've used to script this for many images is https://www.imagemagick.org/

You can get it with https://brew.sh and install quite easily. You should spend 10 minutes installing brew and the command line tools (free) from Apple and skip installing Xcode unless you feel you want the whole developer toolset. That might take 30 minutes or more to install.

There are dozens of tutorials on how to do this - here are three:


https://www.macworld.com/article/1153762/resize_images_automator.html
https://www.macobserver.com/tmo/article/how_to_batch_convert_and_resize_images_with_automator
https://9to5mac.com/2016/04/27/how-to-quickly-resize-images-mac-using-automator-service/