12 volts son, 12 volts meaning direct current. The light bars have built in regulation. 12 24 volt, no switches, connect it and it works. No dimmers no PWM
But just TRY and find a 65-amp T-rated switch. For ergonomics as well as capacity. When switching the light on and off, the throwing of a contact bar on the dash is a bit tough to conceive of.
Control will occur with the switching of high beams. Easy to facilitate. But a relay like this one fills the bill.
Van got whacked by an antelope last week. They cross the highway at night doing forty. Van is totaled, occupants went to the hospital.