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The iPhone 12 only uses one lens at a time to take a photo, so essentially what you want is already what you get.
Remember that at the bottom of the standard Camera app, you can switch between "Photo" mode and "Portrait" mode - and that with the ".5x / 1x / 2x" indicator just above, you can switch between lenses.
Perhaps it is the new lens correction feature for the Ultra Wide lens that is annoying you. You can turn that off from Settings in the Camera section where you'll find a slider for Lens Correction.
I found that by turning off the "true tone" in Settings -> Display and Brightness, it massively changed how the image was represented on the screen. The "oranging" effect or "over lighting" is gone, and the picture looks more natural.
I’ve tried covering every lens on each zoom level to figure out which one is used each time, and it seems lens C is never used?
I own multiple iPhones and can’t help but think this one looks like the actual camera is much more visible and looks as if there’s dust or water Vapor in it.