do i have to switch my sim card

That depends on how to configured the purchase of your new phone. Did you purchase from your carrier? Did you purchase directly from Apple and indicate a specific carrier when you purchased the phone? Or, did you purchase an unlocked phone that was selected using the Set Up Later button. If you worked with your carrier, you probably have a new SIM in the phone. If not, then you will probably need to swap the SIM from the old phone to the new one. And, if you attempt to activate the phone without switching and it doesn't work, then you have to swap.

Glad to hear it. Enjoy your new iPhone.