I just bought a new iPhone XR and it is taking forever to transfer all of my data and it won’t let me install the new update

See the articles below.

Update your iOS device.  -

Get help with over-the-air iOS updates  -

Update – Can’t or can’t restore   -

Have you tried using iTunes on a computer or Finder if running Catalina or later to do the update?

Update software on iOS devices in iTunes on Mac. -

Phone, iPad, or iPod touch - Update with Finder.  *

iPhone, iPad, or iPod touch - Update with iTunes.  *

If you see an error when you update or restore your iPhone, iPad, or iPod    *

Updating iOS: common issues and solutions.  -

So what might happen is that ur new device hasnt the last update and maybe the old one is updated so what i sugest is set up ur device like new update it restore it and start as new to restore ir data

I'm currrious to know how you resolved this issue. I just bought an iPhone 12 mini and I'm having the same problem. I've spent 8 hours or more trying to set up my new phone. I've already restarted and reseted it but it's still stuck trying to download and install iOS 15