Can’t use wired headphones on iMac 24-inch, M1, 2021.
From everything I’ve read, there should be a way to change the output device in System Settings / Sound.
If there is a way, I can’t find it.
iMac (M1, 2021)
If you plug headphones into the iMac's headphone (output) port, then you should see them in the Sound settings.
The headphone (output) port is on the lower left side of the 24" M1 iMac.