Can’t install update on brand new iphone

I just bought a brand new iPhone 12 and ive been trying to transfer everything from my iPhone 7 Plus to the new one, except my iPhone 12 wont download and install an update and it won’t let me set up the phone without updating it. I’ve tried restarting the phone and even wiping it and trying again altogether but it still gets stuck on the ‘preparing update’ page and I can’t figure out why and how to fix it. Any suggestions would be great.