How Can I Overlay Videos In iOS iMovie?

Hello. I've been a user of apple for many years now. It recently hit me that I should try to do some various movie editing for fun. I decided to do the clone trick. If you're not aware of how it works, here's how it works. Basically you record two different videos of something or someone. Next you overlay both clips so that they are synchronized. By cropping both videos you can make it appear that it is one scene, with the same people or things that scene. With that said, I went ahead and looked up a tutorial. Someone was using an older version of iMovie on YouTube and was able to both overlay and crop the videos. So, I got on iMovie and tried to overlay the video files. It didn't work. I could only put one before the other, but could not play them at the same time. So I thought "well, I could at least still crop it". That didn't work either. I could zoom, but not crop. So if someone could tell me how I could do this or why I can't please let me know.

Keep in mind I am only using iOS because my Mac is a 2009 and isn't compatible with just about anything Apple has anymore.

Thanks! 😀