There are three different lenses on the iPhone 16 Pro. Which one gets used is determined by the "zoom" level you pick. The "0.5x" picks the widest angle lens, the "1x" and "2x" use the same lens, and the "5x" uses the third lens.

If you wish to reduce optical distortion and can get farther away from the subject, you'll want to pick the "5x" zoom. Think somebody else here said it was a 105mm equivalent, which sounds about right.

Intermediate values are obviously crops... although given that the 0.5x and the 1x lens are both 48mp sensors (IIRC), and the resulting image is typically 12mp, it doesn't make as big of a quality difference as one might ordinarily think.