Open the SpaceLibrary Scene
Set Transparency to Alpha
Lower the Alpha channel completely
Select the FreeSpace node
Then Export As... MeshLibrary
Overwrite the SpaceLibrary.tres file
If the scale has reverted to 1 in the GridMap
Double click the SpaceLibrary.tres file
Find the Item number representing the trees and rocks
Adjust the scale diagonally
Experiment with decorating your level
Change the floor to look more natural
Rename the CSGBox3D node to floor
Expand its Albedo and choose a grassy green
You may want to darken the road
Add a New StandardMaterial3D
In the color property pick a grey