iOS 12.4 (build 16G5077a) is an official Apple over-the-air update for the iPhone 6s, released on 2019-07-16T17:39:39Z. The update package is 295.74 MB. This is a delta (partial) update that requires 12.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 86c21ac84623f68e7c48597deba2fca71344d9a6.zip.