iOS 12.1 (build 16B5089b) is an official Apple over-the-air update for the iPhone 6s, released on 2018-10-22T17:02:06Z. The update package is 141.19 MB. This is a delta (partial) update that requires 12.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: e8e6ad007c2ce151c7c6c2eceb82ea96d044d9df.zip.