This is a paid asset, but now you can download Cartoon & Stylized HDRI sky Free.
Detail this asset from Unity Store: Original Link
Cartoon & Stylized HDRI sky v1.2 (Latest version)
“If possible, please buy the package to support the developer”
•New HDRI sky texture for Cartoon and Stylized games.
•For now pack has 28 unique HDRI skies + variations. Each sky has resolution 4096×2048 pixels.
•Format textures: PNG, HDR
•Various variants of skybox: night, day, cloudy, sunset, overcast, rainy and others.
•Ready to use setted textures and materials.
•I have plans to expand that pack by adding few new skies every few month.
•So if you are enjoy my pack, please write a review on asset store! Aslo you can leave under review your wishes for skies that you want to see in future.
•Video showcase only how you can use HDRI skybox in your scenes, this pack no include any 3rd content (trees,grass,water etc.).