The ability to search menus is pretty discoverable. The search field is the first thing in the menu when you click the Help menu bar in any app.

But of course the shortcut to jump to the search area is completely undiscoverable, as are many macOS features. You can see it if you go to preferences -> keyboard -> shortcuts -> app shortcuts. (And you can also reconfigure the shortcut key, or reconfigure any shortcut in any app. That feature I love)