iOS 12.1 (build 16B5059d) is an official Apple over-the-air update for the iPhone 6s, released on 2018-09-18T17:20:22Z. The update package is 414.03 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: 340aa8c5c04ec93df8e6466ea6e77c5475a131ed.zip.