I managed to make the grass smaller on my little grass airstrip.
All i did was including a polygon object on the runway. For some reason it only worked on the runway itself, but not on areas without the runway. Or I am doing something wrong.
This is what it looks like in game. Left side is the tall grass, right side is the trimmed grass on the runway.
Here I selected the defined runway object. I defined the runway material surface to “Runway_grass” , which is included as an Asobo standard material. The runway surface is set to “transparent”
Then ontop of the runway I outlined the complete runway with the polygon.
The polygon I set to vegetation, where vegetation scale and density is set to 0. I also ticked “Airport area” and set the surface to the same material as the runway -> " Runway_grass"