for mine I have it set to boot on power in the bios then I have a cord with a power switch that comes out of the back so as soon as I throw the switch the computer boots up. This is the one I have all the outlets are inside the cabinet just the switch comes out the back.
https://www.amazon.com/Master-Electrician-6-Feet-Extension-Outlets/dp/B000W65LO2/ref=sr_1_6?keywords=extension+cord+with+inline+switch&qid=1582503390&sr=8-6