>The camera app for my iPhone 8 sucks. I had to buy another app with actual control over ISO, exposure, focus, etc. I shouldn't need to do that.
You don't need to do that. Why not just use one of the free camera apps instead of paying a premium?
I'm taking a year to work before going to college so I'll be able to upgrade a lot of my hardware. I used to have an S6 that I used for photos and it was great. I see them for $50 all the time so I might try picking up another. Sure, it's still just a phone camera, but it looks pretty good.