iOS 12.1.3 (build 16D5039a) is an official Apple over-the-air update for the iPhone XS Max, released on 2019-01-10T18:09:02Z. The update package is 100.81 MB. This is a delta (partial) update that requires 12.1.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 57838160d28782dca6e4deb1b65586fa885241b3.zip.