in a nutshell, yes.
Easier way to think of it... 87 & 30 are your load side of the relay. one pin (either 87 OR 30) to source and other to device. 85 &86 are a electromagnet coil to activate the relay. One pin to ground, one to the switch with the switch going to 12v... OR you can apply 12v to one side of the relay and the switch is ground.