iOS 12.1.1 (build 16C50) is an official Apple over-the-air update for the iPhone XS, released on 2018-12-05T18:10:11Z. The update package is 493.85 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: 88e51fcb08e7ee62505a0d006b2c07639ed10a55.zip.