Can't do most cold pizzas but it depends on where it is from...like I hate cold Pizza Hut pizza but the local place with the really yummy brick oven pizza fares better as leftovers. Rock hard, dry as hell, cold / room temp pizza is just not appetizing to me.
That said, microwave reheating can make things even worse but using the oven was just too much of a pain. Takes over 10 minutes to properly preheat where the microwave only needs a minute to do it's lackluster job. But now that we have an air fryer, my reheated pizza game has really leveled up.
A covered skillet works really well, too, to re-crisp the bottoms and heat the tops of the slices.