I have been just leaving the Air 2S in Auto for all the camera settings.
I have found the video to be somewhat washed out is the best I can say.
During post-production I have to bump the color adjust for "Vibrancy" to 100 to get a more accurate and vivid color.

I think the default Air 2S color temp is set at 5000 in Auto.   Is there a better manual setting to use for a bright sunny desert?

Thank you

I don't know how you would think that "color temp" or in the case of the "5000" number you are referring to ( actually the white balance) would give you more vibrancy. Are you shooting in any of the log profiles? Those will cause, by design, a "less vibrant/flat" color that is supposed to be  post processed to taste. Also, review your exposure ( use the histogram and adjust from there) because the desert sun will confuse the auto settings but that will usually cause under exposure on details. There are no "better manual settings" that will just work for YOUR particular taste or environment...Learn how to control the camera manually and how the settings affect the images and just practice/learn

I would recommend ND filters especially in bright sunny conditions to bring down the washed out colors you're experiencing. It will help in post processing and ensure the colors you're looking for turn out better.