Switching SIM card from old iPhone to a Sim-free new iPhone

I currently have an iPhone 6s+ that is very old and has started to wear out. I decided to update it to the iPhone 11. If my current phone has a SIM card, is it possible to buy the 11 from the apple website without a SIM card and transfer my old Sim card into the new phone? Will it transfer or will I still need to go to a store and get it changed?