Basic picture-in-picture overlays in iMovie need to stay the same width and height ratio as the project. But by cropping the clip in Project Media before you add it to the timeline, you can crop it as you wish.
Want to know more about how to use iMovie on your Mac? Check out this MacMost course!
Thanks bunches
I thought you did a great job explaining the iMovie Picture-in-Picture overlays and cropping. I'll have to try this next time I'm feeling creative.