A 50mm on APS-C is generally a perfectly usable portrait lens and should not cause unflattering facial distortion if you shoot from a sensible portrait distance. The key point is that perspective distortion comes from camera-to-subject distance, not from focal length itself. If you stand too close, noses can look prominent with any lens; longer lenses just let you fill the frame from farther away.

On APS-C, 50mm often works well for half-body or three-quarter portraits. An 85mm can be very flattering too, but it requires more working room and can be awkward in tighter spaces.

For your use—wedding portraits on the beach near sunset—a fast 50mm is a practical choice if you want versatility beyond tight headshots. An 85mm is better if you prefer standing farther back and want stronger background separation, but be prepared to need more space.

A good way to decide is to test your zoom at 50mm and 85mm and see which framing and working distance feels better. Also, extremely wide apertures like f/1.2 are often unnecessary for portraits because depth of field can become too shallow.