Transferring locked iPhone data to new unlocked iPhone

I have an iPhone 8 I bought from Verizon in '18. I'm upgrading and considering an unlocked, refurbished iPhone 13 or 14 (or even 15, haven't decided which yet), keeping Verizon as my service provider.

Question I have is, how do I transfer all contents from the existing, locked iPhone to the new, unlocked one?