iOS 15 preparing update on new iPhone

i purchased a brand new iphone 11 today, everything went smoothly in the setup until it came to downloading the new software update. it has been stuck on ‘preparing update’ for over an hour. i had updated my old phone to ios 15 a few days ago and it only took about 15 minutes. all the solutions to update it involve settings, but since it’s a new phone i’m stumped. what do i do?

[Re-Titled by Moderator]