iOS 12.1.3 (build 16D5037a) is an official Apple over-the-air update for the iPhone XR, released on 2019-01-07T18:07:14Z. The update package is 326.78 MB. This is a delta (partial) update that requires 12.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5366745e22bfca74443de85c2ea0d9120da6fb4e.zip.