I personally don’t think it is a dealer plate. In Arizona, the temporary license plate you get when you purchase a new car is a white piece of paper, I’ve added a photo of an example (I edited it to obscure the plate number).
As you can see, the brand of car is abbreviated on the top right corner of the temp. plate. In the photo of the Range Rover I can see either “DR” or “OR” at the top right of the plate, under the paper which I think would be the end of the abbreviation for Land Rover.
I can only think of seeing deep blue metal dealer plates here in Arizona (photo added as well).
Edited to add links, sorry
@tricia 
!
Link for example of temp plate:
Print
(My photo shows real world example but I don’t want to dox the real license plate number, I can change out the photo if needed)
Link for dealer plate:
Motor Vehicle Dealer License Application Process and Account Set Up | Department of Transportation