you can simply just every player point using this guide, and editing it to use player points and gain each players hitbox points for future reference.
also, this theory is for Psuedo projectiles or real projectiles once someone figures out how to detect them, or Psuedo melee attacks. I will note that the hitboxes do NOT need to be around the player, this can be used to make placeable turrets that slow players down that players can place.
you can adapt the theory into code in whatever way you choose, I might go about making a guide on how I personally did it for those who are stuck on how to implement this.