Make a screen recording smaller without making it worse
File size is resolution times length times how much changes on screen. You control the first two before you record. Knowing which one is doing the damage is most of the fix.
Resolution is the big lever
Going from native to 1080p on a modern iPhone roughly halves the pixel count; 1080p to 720p more than halves it again. For screens with normal-sized text, 720p is readable and a third the size of native.
Length is the honest one
A recording that is twice as long is twice as large. Record what you need, plus a few seconds each end for trimming, and stop. Long idle stretches with nothing moving compress well, but they are still minutes nobody watches.
Motion
A static settings screen costs almost nothing per second; scrolling a photo feed or playing a game costs a lot. You cannot change what the app does, but you can not scroll for the sake of scrolling.
What not to do
Do not re-encode with a third-party app to shrink it before uploading. The platform will re-encode again, and two lossy passes look worse than one. Record at the right size instead.
Does the camera bubble add much?
Very little. It is a small region of the frame.
Does two-track audio make the file bigger?
Slightly — audio is a small fraction of a video file either way.
