This is a paid asset, but now you can download Space Graphics Planets for FREE, but please remember this package is provided only for learning purposes or to be able to test before buying the product, NOT FOR COMMERCIAL PURPOSES.
Detail this asset from Unity Store: Original Link
Space Graphics Planets v4.0.3
Enhance your space scenes using this large pack of high detail volumetric planets. These planets are finished using the powerful planet features from Space Graphics Toolkit (not required).
💡 Full Customization ― Quickly tweak all planet visual settings to achieve the exact visual result you want. Realistic worlds, fantasy worlds, atmosphere height, atmosphere color, sunset color, and much more!
💡 All Render Pipelines ― This asset supports the standard pipeline, as well as HDRP, and URP. See HERE for more information.
💡 Dynamic Water Level ― All planets in this pack feature a dynamic water level, allowing you to achieve different looks, or even add new gameplay.
💡 Volumetric Atmosphere ― Seamlessly travel in and out of the atmosphere from space, and admire the atmospheric scattering of the sunlight. This feature has been highly optimized, and each visual parameter is fully customizable.
💡 Planetary Shadow System ― Enhance your scene with high performance dynamic shadows cast from planets and moons, allowing you to create eclipses and much more. These are compatible with normal shadows, and allow massive bodies to accurately block light in your scene.
💡 Planetary Cloud Layer ― Add a layer of clouds above your planet that can rotate around and fade out as you approach.
This asset uses the VarelaRound font under SIL OFL 1.1; see Third-Party Notices.txt file in package for details.
This asset only contains some of the features from the full Space Graphics Toolkit asset. Advanced features like dynamic planet LOD are not included.