i want to switch my iphone with verizon service to comcasat and need to know if my contacts and emails will switch over and stay with iphone or not

You don’t need to do anything; changing carriers does not alter any data on the phone. The only issue would be with a Verizon email account, which you presumably would lose if you have one. But you should be backing up the phone regularly, regardless of switching.

Nothing is stored on the SIM card.

Switching service providers should not effect anything stored on your phone.