Apple doesn't make any attempt to take advantage of its different screen sizes. The Pro size phone seems what they base their calibrations on. The Pro Max shows exactly the same view but bigger. The mini is the same again, but everything on screen is smaller. I've had a 12 Pro, a 13 mini, a 13 Pro Max and a 14 Pro Max, as well as all the others back to the second iPhone iteration. Personally I found the mini unusable because everything on screen was tiny. The Pro Max looked like someone had just enlarged the screen, like a photocopy where you take an A5 document and output it as A4.
I've had so many phones over the years, all different screen sizes and operating systems, and have been aware that the manufacturers/developers have crafted the design and fonts to make them more readable on a smaller screen. Likewise, on larger screens efforts have been made not to waste the extra space available. Nokia did this very well with its Windows Phones. Apple does precisely nothing. You get the same screen content but bigger or smaller.
When I thought about this I realised that as long as the screen looks clear to my vision-corrected eyes there is no point going for a larger device. I don't watch media or play games on a phone, so that is not a factor in my choice. The 15 Pro it is!