Google Earth has a default style setting for imported polygons that drives me crazy. They are set to 100% opacity, "white", with the random selector enabled, meaning they show up by default after being imported as a rainbow of randomly colored, opaque polygons. Is there any way to change this default style setting?
If you import data from some other format, such as a shapefile, then Earth Pro asks you if you want to apply a style template. If you select yes, then it gives you some basic styling options, including what field to use for the feature names, some color settings (including turning off the color randomization), and icon and height settings. At the end of that process it asks if you want to save the styles you set as a "Google Earth style template" (.kst) file. Once you have that file, you can apply it to future data imports.
More details are available in the Google Earth Help documentation: https://support.google.com/earth/answer/176685