I tried the suggestions on Turn off display in Windows on command and they aren't suitable.
The Screensaver method only blanks the display without turning it off. Maybe that would work for OLED users.
SendMessage with the params -1,0x0112,0xF170,2 does turn off the display, but it does so by putting the computer into connected standby. This interrupts media which is currently playing, such as YouTube.
I attempted to use DisplayPowerOff, but it doesn't work.
Note: I had about ten minutes where I could indeed turn off the display using either DisplayPowerOff or the powershell SendMessage method, but I think that was a glitch because I can't replicate it.
I tried changing the Console lock display off timeout attribute to 2 in Power Options by enabling it with a registry edit, but it doesn't help me. Prevent Windows 10 from going to sleep on lock screen
I am out of ideas.
Note: Yes, you could set closing the lid to Do Nothing, but then I can't leave my lid open, it's inconvenient for me as I'm sitting on my bed next to my desk man it's within arms reach, and I have to remember to change the Power Plan later. I just want to be able to turn the screen off without putting the laptop to sleep or closing the lid.