iOS 12.1.3 (build 16D40) is an official Apple over-the-air update for the iPhone XS Max, released on 2019-01-22T18:15:06Z. The update package is 506.88 MB. This is a delta (partial) update that requires 12.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: d06bd935eb668a801229eadf4749765e1eff012d.zip.