A good Sky Preset acts as a combined with a HDR (High Dynamic Range) texture . With a single click, you get realistic sun positions, atmospheric haze, and accurate cloud formations.
(now part of Poly Haven) – 100% free, CC0
or a large sphere with an emission map to create their skies. You can download free high-quality HDRI maps from these specialized sites: HDRI Skies pack 3 HDRI Skies pack 3 - HDRI SKIES. Hdri Skies HDRI Skies pack 2