- Right click on the dock > Layouts > Configure…
- In Settings window, go to Preferences tab
- In Actions section > Tick Press ⌘ to activate Application Launcher
Or
-
Open ~/.config/kwinrc, then add:
... [ModifierOnlyShortcuts] Meta=org.kde.lattedock,/Latte,org.kde.LatteDock,activateLauncherMenu ...
-
Reload KWin:
$ qdbus org.kde.KWin /KWin reconfigure