Should have an option to either resize the actual file or the display in the Anki interfaces

Would be awesome

This would be AMAZING I would pay for this!!!!

The review window isn't always the same size, so I don't see how this is helpful

Maybe something that tells you how many pixel will be the definitive picture while you resize it dragging the corners

As another commented, image size you view in editor is not the size you will see in reviewer. Image style editor addon is I think good enough alternative

You can now all crowdfund this add-on on https://www.kickstarter.com/projects/arthurmilchior/image-resizing-in-anki?ref=project_build