iOS 12.1.3 (build 16D40) is an official Apple over-the-air update for the iPhone XS Max, released on 2019-01-22T18:15:07Z. The update package is 388.66 MB. This is a delta (partial) update that requires 12.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6dd26b0f5fc80b2232300ec77ce9359d112cde54.zip.