To reset the SMC on Mac desktop computers with a T2 chip, including... iMac Pro Mac Mini from 2018 or later Mac Pro from 2019 or later
Check it has a T2 chip in "About This Mac" from the Apple menu.
To reset these desktop Macs: Shut down the Mac and unplug the power. Wait 15 seconds. Plug the power cord back in. Wait 5 seconds. Start the Mac normally.