Got a new iPhone 15 pro, am transferring info from my iPhone 13, and get stuck on the software update to ios18. Tried three times, waiting over an hour each time.
Check compatibility: Go to Settings/General/Software Update, and it will tell you the most recent version of iOS that your iPhone is eligible for. In some cases immediately after a new version is released you will be given a choice of an update to the current version or to the newer version; for a brief period you can choose either.