After the land terrain is defined, we can give it thickness depth to be able to see the land terrain as a mass.
Select the terrain and click the right mouse button. Click the Properties line with the left button from the menu that opens .
In the dialog that opens, check the Floor Soil base option at the bottom .
Enter the value you want in the active depth line.
Assign a material that you find suitable for the land in the material section.
After this process, the land will appear as a mass on the 3D screen.