Downloads for iOS and watchOS updates usually start at about 6pm UK time (1pm in New York; 3am in Sydney). All Apple smartphones from 2017’s iPhone 8 or newer can install iOS 16. WatchOS 9 requires an iPhone 8 or later to be running iOS 16 first. Then open the Watch app and navigate to General > Software Update to begin the installation. Apple has decoupled security updates from full iOS updates, allowing it to release bug fixes faster and have them automatically install on user iPhones.

Source: The Guardian September 12, 2022 21:15 UTC