This is a paid asset, but now you can download Toon Skyboxes Free.
Detail this asset from Unity Store: Original Link
Toon Skyboxes v1.0
“If possible, please buy the package to support the developer”
Toon Skyboxes perfect for any stylized background.Fill up the backdrop and add mood to your game with collection of 10 Skyboxes.
-4 Day Skyboxes
-2 evening Skyboxes
-4 Night Skyboxes
We will be adding more to this collection with time.