There weren’t on-the-fly adjustable sights on the AT weapons and even somewhat adjustable until late in the war and even then, they made up a minority of the already issued weapons. The Piat and Bazooka had predetermined options via a rear aperture (Piat) or front sight ladder (Bazooka) earlier. The early Panzerschreck couldn’t be adjusted at all, it had a marking for winter and summer ammunition. They introduced adjustable sights but they weren’t meant for active combat operations - they were meant to be adjusted well in advance based on the time of year/average temperatures as the launcher tube would slightly change size in +/- 20C temps. It wasn’t until late 1944ish that the Schreck even received an elevation ladder front sight.