You can open them using Spotlight. Just press Command + Spacebar on the keyboard.
The Spotlight search window will open.
Type in the name of the app you want to open and then click on it in the results. The app will open right up.
Another option is to open Siri by pressing the Siri icon or pressing and holding Command + Space until Siri opens. Then say “Open” and the name of the app once the search window opens.