Desertwave is a aesthetic that can be described as a combination of Synthwave and Westerncore. It focuses primarily on the deserts of the southwestern United States and Mexico, reptiles, and 80s new wave rock groups, such as Oingo Boingo, Talking Heads, and Wall of Voodoo.
The fashion of Desertwave includes elements of what most people thought of that particular area of the country at the time (lots of vests, sombreros, ponchos, and light, airy clothing that won't cause you to overheat due to the immense heat that deserts tend to have during the day).
In terms of make-up, the popular Día de Muertos look is a popular look to try and achieve (especially around Halloween/Día de Muertos), especially the Calavera (or Sugar Skull, due to it often being used to design sweets for the day), or otherwise going for a more minimalist look, like you're going for a walk in the desert.
These videos should help give you a rough idea of what the Desertwave aesthetic would look like.