v20.12 (Win10) 2x monitors
1) Drag the project tab to 2nd monitor.
2) Click on [Switch Full Screen] (right hand side toolbar) in the Project Monitor window.
The window extends to full screen. A grey bar at the bottom without any control buttons.
3) Move the cursor in the Clip Monitor.
A blank Project Monitor pops up while one Project Monitor is in full screen mode.
4) Close the blank Project Monitor.
5) Repeat step 2.
It switches the Clip Monitor to full screen, instead of restore Project Monitor window.
From now on, the right hand side toolbar in the Project Monitor is controlling the Clip monitor.