A mechanical 3 pin switch uses center pin (POLE) to switch to Normally Open (NO) or closed (NC) positions.
It depends if it is a slide switch, , rotary or toggle switch.
For low current, you may need to bypass cap to clean non gold plated contacts from oxide.
For better reliability, gold plated switches are used ( <2A)
For simply switching on CPU power , a 2 pin slide switch is all that is normally used on PCB or a toggle switch on Panel or a push-push button for toggle ON-OFF but still single pole single throw or SPST or 1P1T
For semiconductor double throw switches we use two switches P(+) & N(-) to make a bipolar switch like CMOS.
For single POLE , we can use a semiconductor " High Side Switch" common to automotive use.
A double pole (2T) electronic switch for power is usually called a 2 pole bridge driver.