Just to confirm, this was an encrypted backup in iTunes or an iCloud backup? I used the former and most apps (that I've checked so far, anyway) were still logged in, my authenticator app was all set, and it really was a breeze to get started with the new phone.

One thing I really like with iOS 12 is the further integration of LastPass (and others like 1Password) etc. into the system so they can be used instead of Keychain - so much easier now.