Apple has launched iOS 13 and watchOS 6, as well as — to a limited degree — its Apple Arcade gaming service.
You can download iOS 13 on your iPhone by going to General > Software Updates. iPadOS is coming Sept. 24, and iOS at the end of the month. macOS Catalina is due in October, probably along with new Macs.
watchOS 6 can be downloaded for free through the dedicated Apple Watch app on the iPhone by going to General -> Software Update. To install the new software, the Apple Watch needs to have at least 50% of battery life, needs to be placed on a charger, and close to your iPhone.
You can access Apple Arcade through the App Store on your iPhone using the new Apple Arcade tab in the navigation bar. As for the Mac and iPad, it’s still “coming soon.”