Sonny, you are killing me here!
Getting back to the original question. The room service will not wrap up sandwiches to take off the ship. It is "room" service not "carry-out" service.
I can't find any Carnival policy about taking a sandwich off the ship though. And they certainly don't screen for it while going ashore. I would not recommend it because the food could spoil. Then what? Someone gets sick and blames it on Carnival's food.