iOS 10.2.1 (build 14D27) is an official Apple over-the-air update for the iPhone 6s, released on 2017-01-23T18:08:35Z. The update package is 1.1 GB. This is a delta (partial) update that requires 9.3.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 80c3a6243c4389381407ac473fc01c265688f137.zip.