How can I check if a player is in a Region3?

The question is in the title, thanks for help!

You can check for their Humanoid or HumanoidRootPart. However if npc’s exist you can check if the model’s Name is in the player’s list.

You can use FindPartsInRegion3, then you can check if the part is a child of a player Model, and you know the player is in Region3