So, multiple monitors are working fine on my Mac OS 10.15 running Win 10 on Fusion 11.5.5.
But, if I start the VM, then plug in an external display, the 2nd display is not available in Windows, and I get a Windows alert chime.
The Virtual Machine library window, with Win 10 VM selected, will, however, show 2 displays.
I can fix this by switching from Full Screen to Single Window and toggling the 'Use All Displays In Full Screen' View menu item, and then go back to Full Screen.
Is this something that can be remedied in Fusion, or is it a Windows thing that I'll have to live with?