watchOS 6.3 (build 17U216) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2021-01-26T18:26:23Z. The update package is 170.67 MB. This is a delta (partial) update that requires 6.2.6 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: ef212a56b9c91e7c86b13444cd45a05054a5ebe3.zip.