I just ordered my wife a new Samsung 7 phone because she doesn’t like her moto g4 plus. When I get the phone is all I have to do is move her SIM card from the old phone to the new one to get her up and running.
Likely, that’s all it will take. In any event, if you ordered the S7 from Republic, a new SIM (if needed) is included.
Transferring user content (as opposed to service) is a different matter. For that, you might want to look at: Samsung Smart Switch Mobile - Android Apps on Google Play.