This article explains how to add apps directly to your Apple Watch running watchOS 6 or watchOS 7. For watches running watchOS 5 or earlier, use the Watch app on your iPhone.
How do I install all apps on my Apple Watch?
It includes information about deleting apps from your Apple Watch, changing the app layout on your Watch, and displaying apps on the Watch Dock.
On Apple Watches running watchOS 5 and earlier, you add apps to the watch from your iPhone. In watchOS 6, Apple introduced an on-watch App Store, so you no longer have to add apps using the Watch app on your paired iPhone; you can do it right from your wrist.
The Apple Watch App Store in watchOS 6 and later only contains apps that run on the watch. Follow these steps to view and download apps.