Here are excerpts of the relevant laws:
RCW 46.37.040 Head lamps on motor vehicles.
(1) Every motor vehicle shall be equipped with at least two head lamps with at least one on each side of the front of the motor vehicle, which head lamps shall comply with the requirements and limitations set forth in this chapter.
(2) Every head lamp upon every motor vehicle shall be located at a height measured from the center of the head lamp of not more than 54 inches nor less than 24 inches to be measured as set forth in RCW 46.37.030(2).
RCW 46.37.220 Multiple-beam road-lighting equipment.
Except as hereinafter provided, the head lamps or the auxiliary driving lamp or the auxiliary passing lamp or combination thereof on motor vehicles shall be so arranged that the driver may select at will between distributions of light projected to different elevations, and such lamps may be so arranged that such selection can be made automatically subject to the following limitations:
(1) There shall be an uppermost distribution of light, or composite beam, so aimed and of such intensity as to reveal persons and vehicles at a distance of 450 feet ahead for all conditions of loading;
(2) There shall be a lowermost distribution of light, or composite beam, so aimed and of sufficient intensity to reveal persons and vehicles at a distance of 150 feet ahead; and on a straight level road under any conditions of loading none of the high intensity portion of the beam shall be directed to strike the eyes of an approaching driver.
RCW 46.37.270 Number of lamps required — Number of additional lamps permitted.
(1) At all times specified in RCW 46.37.020, at least two lighted lamps shall be displayed, one on each side at the front of every motor vehicle, except when such vehicle is parked subject to the regulations governing lights on parked vehicles.
(2) Whenever a motor vehicle equipped with head lamps as herein required is also equipped with any auxiliary lamps or a spot lamp or any other lamp on the front thereof projecting a beam of intensity greater than 300 candlepower, not more than a total of two of any such additional lamps on the front of a vehicle shall be lighted at any one time when upon a highway.
Read more here:
https://www.bellinghamherald.com/news/traffic/rules-of-the-road/article22250220.html#storylink=cpy