This Unreal Engine 5.5 video is about getting a better understanding of how KillZ works, and how that relates to Player Respawn or Restart.
We start by showing the KillZ World Setting, talking about how it works, and setting up some basic Respawn/Restart logic. We then go over some complications with that and how to work around them. Next, we add a KillZ Volume, and show that it works the same way as falling out of the world. And we follow that up by looking into the Engine C++ code to see that both cases are calling FellOutOfWorld() on the Player Character Actor. We then override this function and provide a call to a Blueprint function where you could add some logic, an animation, reset the position of the player, or ultimately call DestroyActor.
https://dev.epicgames.com/community/learning/tutorials/m661/unreal-engine-understanding-unreal-killz-and-respawn