I would be more inclined to call this area “Juniper Sand Trails” than Dunes.
The majority of the area is covered in scrub brush. Pick a direction you want to go, and there are sand trails through the brush headed that direction.
There are a few open dune areas. Taller dunes can be found further out. There are hundreds of little sandy hill climbs. All of the “mainline” sand trails that are used to get around are all whooped out. A power line runs across the area, and a petroleum pipeline runs the length of the area. Using those markers, it is easy to find your way back to the parking area if you get lost.
Get details including directions, staging areas, maps, and difficulty levels in the UTV Guide to WA State.