I created a quick overlay to help with formatting videos for YouTube Shorts, updated March of 2023. I couldn't find one online so I threw one together real quick. It gives you a good idea of where the action buttons are so you can keep your content always visible. YouTube also zooms in on your content ever so slightly so there's black bars on the sides to account for that.
You will receive an email to download the PNG file. Check your Junk folder just in case.