if you signed in with Google or Apple or, for example, Verizon, all of these sync your contacts. also remember that if you did on the phone before, this can even restore from there. so simply by logging into Samsung or Google with your next device you can get your contacts.
You can also use Samsung or Google find and erase your phone and/or extra password it so your personal information isn't compromised. If it shows where your phone is, you have somewhere to point law enforcement to. The phone does not have to be registered just signed into either or both accounts. FYI, the first time you sign into your Samsung account on a new device, the device is registered automatically. Your phone would have automatically synced your contacts with Google unless you specifically disabled that feature, so you should find your contacts by going to contacts.google.com.
