I cannot turn off sos on my new 16

You dont turn off SOS, it means you are not connected to your carriers service.

You may need to contact your carrier for help -

If you see SOS, No Service, or Searching on your iPhone or iPad - Apple Support

That means that you don’t have a connection to ANY mobile carrier.

Have you installed the nanoSIM or eSIM in your phone ?

SOS means that you do not have any cell phone service except the ability to make emergency 911-type calls – to contact the fire department, the police, or an ambulance. In some countries, carriers are required to put through such calls even if you don't have cellular service with them.