Is the sigma 20mm f 1 4 dg hsm art good for landscape?

Yes, I think it's a good choice for landscapes, with one caveat. At 20mm on full frame you get a properly wide view, and it's made for Canon EF, Nikon F, Sony E and L-Mount, so there's a good chance it fits your camera.

Landscape work is slow, and the landscape page notes that you can use a tripod. That suits this lens, because it isn't stabilised. Most landscape shots are taken at narrower apertures to keep the whole scene sharp, so the f/1.4 speed will be a bonus you rarely use there. It earns its keep for night skies and dim interiors.

For a full-frame body to pair with it, try the Sony a7R V or the Nikon D810.

Written by Claude from this site's pages.