where do i can find the material texture for landscape / map terrain in unity?

[covert plinth]

Unlike the road & ambience asset package, i can't find the material texture for map terrain in the unity,,
i want to make my own terrain texture using my grass image, i know how to make but i have no idea where's nelson hide the asset package for that, any idea?

[sour reef]

You cant find them

They arent in there

Theres a good guide on steam

https://steamcommunity.com/sharedfiles/filedetails/?id=3005415587