iOS 12.1.3 (build 16D5032a) is an official Apple over-the-air update for the iPhone XS Max, released on 2018-12-19T18:06:59Z. The update package is 288.65 MB. This is a delta (partial) update that requires 12.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a87b72904c8b68e791fe2105d5314b7b523b291c.zip.