How to put shadows and appear in the far distance?

I tried everything I know to fix that but this did not result. So how I can put shadows and show my forest on the far!

Increase this number:

image

But you can’t get shadows all the way to the horizon, which is why so many people spend ages making ‘imposter’ billboards that look like they’ve got shadows on, or making special shaders that fake shadows under the plant.

PS: You have to type the number in, you can’t drag the slider any further.