iOS 12.1 (build 16B92) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-10-30T17:16:25Z. The update package is 1.67 GB. This is a delta (partial) update that requires 10.3.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 64213b508d97499590f0551f04da81487e76ed2a.zip.