iOS 12.1 (build 16B92) is an official Apple over-the-air update for the iPhone 6s, released on 2018-10-30T17:17:02Z. The update package is 1.28 GB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f4f7086db2bd1c3d10f4f1f70bf6ece5ff1c799b.zip.