Layout's Physical Sky background shader has received an update to add a softened horizon line, and a "ground" that can be colored to suit your needs. There are no new controls, but rather than the hard line going to black of previous versions of LightWave 2019:
There is now a softer line that should provide a more realistic impression of a physical sky.
If you now add a Textured Environment, and made sure it is above Physical Sky in the Environment list, you can have something like this:
Note that Physical Sky is a background shader, so there will be no "perspective" whether you use an image or a texture.