Sun & Sky?

How do you usually setup the Sun & Sky so that the horizon line just doesn’t stop at a harsh black line?
Isn’t there a way to wrap the Sky 100% around… like a Sky-Dome?

I dont’ recall how I did it, but it can be done by fiddling with one of the values on my exponential height fox, if you change fox max opacity that has some effect on the black, not sure enough to get rid of, also you can try fog cutoff distance, as moving slider affects that also.

I suppose you mean the horizon that in your case looks dark. That is the end of the sky and the start of the ground. You can adjust the volumetric HeighFog actor or eventually try to find a better settings in the Rayley and Mee

Alternatively you could make a sky-sphere mesh (needs to be pretty large, and properly cut). Wherein you UV the inside to be a mirrored copy of the top.
If you haven’t watched this, it explains how to deal with the materials: