Open… ⌘O — Logic Pro X keyboard command of the day

  Open…    ⌘O

Open a file. The command opens the “mini-Finder” window and allows you to search for and select a file that you want to open. There is no specific selection tool for choosing a file type. You can open projects, audio files, MIDI files, and others.

This is the standard Open command found in virtually all Mac applications.

Open Logic Pro projects — Apple Support

You can also open a Logic Pro project (or a MIDI file) by dragging it onto the Logic Pro icon in the Dock.