This video is a great explainer on heat pumps [1]. The TL;DR is that they are essentially nothing more than air conditioners that run in the opposite direction. Plus, a heat pump and an air conditioner can be combined into a single system.
Not just can be combined they effectively always are. I’m not aware of any residential heat pumps sold in the US at least that don’t also operate in cooling mode. The additional cost is basically just a reversing valve.
1: https://youtu.be/7J52mDjZzto