I doubt one will see noticable differences between the cameras to be honest. The iPhone 12 line has a 12 MP front camera now and night mode on all the cameras. If you really need the RAW editing capability, get the 12 pro. If you do a lot of video where extra stabilization and slightly reduced noise is paramount, get the Pro Max. If you want an unobtrusive camera to take everywhere, get the mini, a powerbank and a selfie stick.
The sensors themselves are not where the magic is happening nowadays, it's mostly in the processing and Apple has a pretty big lead in that department. Other phones may have far superior optics and sensors but the overall result usually isn't consistently as good overall.
Big lenses, big sensors and OIS require lots of space and weight, it just ain't gonna happen on a small phone. Just pick a phone size that works for you and trust the engineers to get the best out of the tiny hardware. And learn how to use that camera; people I travel with are often pissed that the pictures from my 2016 iPhone SE look better than what they shot on their new flagship phones because they don't even bother with framing or adjusting settings.