Can I use my new iPhone while my old one is still backing up?

Hello, my new iphone has just shipped in (the iphone 15) and I currently am using my old phone (iphone 13) and I have been trying to backup the stuff on my current phone before I use my new phone. My question is, can I use my new one while out and about at work and stuff while my old phone is still backing up and then get that data from my old phone onto my new phone later? My current back up time said it has to rake about a day to back up but my backup has been stuck at the same exact spot since 3 pm, it is currently 8 pm.

[Re-Titled by Moderator]