Never made a turn based game but my approach would be letting the game mode decide who’s turn it is and call an RPC method to enable/disable the player input on the controller (PlayerController/AIController)
When u draw a card, locally check if the input is enable, if enable call an RPC for drawing the card. The server RPC handler should also check if input is enabled to be sure.
Maybe add a BeginTurn/EndTurn to the controller.
Blueprints are not really needed, at least no blueprint “programming” if u do in c++, u will always need a bit of blueprinting like making your pawn BP where u set the mesh and stuff.