Historically, the Italians produced the Carro Armato P.40 “heavy tank” just before the war ended for them. Although, it was really more like a medium tank, the Italians called it a heavy tank. You can get it from the HBG site from the global war expansion area. I have not ordered it yet so I don’t know if it is physically larger than OOB tanks or not.
The only minor that had access to heavy tanks was Hungary which had a few Tiger I tanks given to them by the Germans.