Is it possible for players to extend my games game-mode class for custom GameModes?

Hello, I have implemented steam workshop and plan to support custom game-modes like GMOD does.
I was thinking of how to allow users to write their own game-mode based on UE4’s gamemode class.

I thought, if I was to upload a folder- MyCustomGameMode with a .cpp and .h file inside it, of course with the proper syntax

class MYGAME_API AMYGAMEGameModeBase : public AGameModeBase

would I be able to load it as a game-mode as is? Or would I have to write a custom game-mode importer?

Thanks for any suggestions!