This is where you control the terrain dimension and scaling:
• Chunk Size: Size of a terrain chunk, 32 is balanced between procedural and sculpting operation. Currently it’s not available for tweaking. This value is used for editing; you can set a different value when building the final terrain.
• Width: Size of the terrain on X-axis in world space.
• Length: Size of the terrain on Z-axis in world space.
• Scale: Scale of the terrain on both X and Z-axis.