Should I swap sim cards from IPhone X to IPhone 11 Pro Max

I recently bought an IPhone 11 Pro Max from the Apple store with the intent to trade in my iPhone X. However I’m not able to switch my cellular plan from the X to the 11 pro max after I set up the iPhone 11 Pro Max. Are the SIM cards compatible and should I just switch them to put my data plan onto the new phone or is there another way?