Using small PNG as overlays on a.MP4

I am doing stop frame animation (NOT using Stop Motion Studio) and have created small PNG graphics (50pix X 35 pix) and want to place them, at that size, over a 1280 X 720 H264 .mp4 in Final Cut Pro on an iPadPro (M1/iOS 16.4.1). I import them as files, not photos, into FCP. When I try to place them over the .mp4 they blow up to 1280 X 720 and not the size I created them.

I am using Dragonframe to create movies of Lego minifigures and the PNG graphics are different facial components, i.e. eyes, mouth, facial hair. Why are these PNGs getting scaled up so large and is there a way to get them to come in at the 50 X 35 size. The smallest scaling available in FCP is 25% which gives me a 320 X 180 image which is fuzzy AND much larger than the Lego minifig.

I was hoping to be able to do compositing on the iPad but it looks like I'm going to have to find my old copy of FCP on the iMac if it will even run on Catalina and dump trying to do this on my iPad.

Thanks for any help!!

Best,

Joe B