Apple makes this very easy. I broke an iPhone and bought a replacement. If you have iCloud, you login to the new phone and you can see which backups you can recover from. If you are transferring a phone, say you upgraded, it’s even easier. You can also image the phone with a connected laptop and store it on a backup drive, which is nice to not use up iCloud limits.

The transfer and backup system are pretty much the same mechanisms.

Restoring is probably order of ~1 hour to go through all the setup. Then some hours to sync any data and updates that need to be redownloaded, apps reinstalled, etc.