I'm using a 14 Pro under iOS 17, but I would imagine the settings will be pretty much the same as on your phones.
I had originally purchased a regular 14, but the color on all shots were oversaturated, and there weren't enough controls. I sent that back after a couple of days of testing and got the Pro model. Much, much better. After going through the settings and testing to see what does what, I now get photos and video where the color on my Mac matches what I was looking at.
Try these:
Settings > Camera
Photographic Styles - make sure it's on Standard so the phone isn't trying to stylize the captured image.
Formats - I have High Efficiency turned on. Important, turn on ProRAW & Resolution Control. The choice under that then activates. Tap Pro Default and set it to ProRAW Max. This makes a huge difference in how the phone manages color. Also turn on Apple ProRes so the same type of advanced color management is applied to your videos.
The ability to lock the lens is already there. Don't just tap to pick a focal point, tap and hold. A yellow AE/AF Lock box will appear, showing that your focal point won't change. Once locked, if the scene is too bright or dark, slide your finger up or down next to the focus box to change the exposure.
