Minecraft wiki entry for Pillager_Outpost, associated text: Both regular pillagers and pillager captains can continuously spawn around the structure. Pillagers can still spawn if a player is inside the tower.[needs in-game testing] In Java Edition they spawn in a 72×54×72 area centered on the top level of the watchtower, the same level as the chest. In Bedrock Edition, they spawn at or below a particular location in the outpost; specifically, they choose the northwest corner of the highest opaque block with a non-solid block on top.