When iPhone repair status is complete what happens to iPhone I sent in?

3 options under my AppleCare subscription so choose express replacement which I got so sent my iPhone 14 back with a cracked back glass ,my status is now saying repair complete , what happens now

will I get my old back or do I keep the replacement ,dubious on putting passwords on this if I have to sent it back

thanks for your help

[Re-Titled by Moderator]