iOS 15.7.4 (build 19H321) is an official Apple over-the-air update for the iPhone 6s, released on 2023-03-27T17:12:44Z. The update package is 3.41 GB. This is a delta (partial) update that requires 12.1.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f643ac4f051bc837cc9d68bb07aa0ce67c448daf.zip.