Welcome to Android Central! Just to be sure -- you inserted a valid SIM card? Or are you using the eSIM for Google Fi?
How did you save your contacts on your old phone -- were they saved to your Google account in the cloud, or only the local Phone account?
Are you using a Google backup of the old phone to restore to the new phone? What phone is the old phone, and what Android version is it running? Older versions of Android had much more limited backup ability.