MSFS only supplies the snow as of now. There are a few options to change the trees and the ground. Check out Accuseason by Rex and the products sold in the marketplace (and elsewhere) by Bijan. The latter provides a mask that gets rid of that green look in winter, and the former (Accuseason) is working on it.
I had Bijan’s products, and they are very nice, but he has gone missing due to some personal reasons, so I switched to Accuseason.