iOS 12.1 (build 16B92) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-10-30T17:16:30Z. The update package is 1.28 GB. This is a delta (partial) update that requires 11.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9fb9c9fec1f72bbd51fae7015dddc0660f74f2bd.zip.