A DLC unlocker is a software tool or a crack that allows players to access DLCs that they haven't purchased or don't have access to. These tools usually work by modifying game files or bypassing digital rights management (DRM) systems. In the context of Civilization 6 on the Epic Games Store, a DLC unlocker would enable players to access all the DLCs, even if they haven't been purchased or aren't available on the store.