[CentOS] Reboot/shutdown without login

Mon Jan 11 18:23:04 UTC 2021
Kenneth Porter <shiva at sewingwitch.com>

I installed CentOS 8 on a Dell server and it's been running fine as a 
headless system, admin'd remotely by ssh. Now I'd like to allow someone to 
shut it down at the console without logging in. Is there a way to do that? 
Or do I need to get the GUI working?

I tried switching it into graphical mode ("systemctl isolate graphical") 
and the console freezes with nothing but a non-blinking text cursor at top 
left. The usual virtual console switching hotkeys (ctrl-alt F1-F7) don't do 
anything when it's hung like this. The system is still responsive in my ssh 
session. It doesn't recover if I switch back to multi-user target so I have 
to reboot it to make the console useful again. I'm guessing I'm lacking a 
good video driver. (It's an R720xd I inherited and the latest drivers on 
Dell's site are for RHEL 7.)