These books have all been created from the original "Magic Book" asset: https://www.artstation.com/artwork/9v4LO
The geometry has been modeled and UVed in Maya. The texturing have been done in Photoshop.
I created a version of the book that still has the name (as the original Magic Book asset) as well as an alternative version without the name and with a different decoration color (silver instead of golden). The pages inside the book are also different compared to the "Magic Book".
Both book covers are of a neutral color, so I can multiply any color I want in Unreal.
As all my other textures the Photoshop file is pretty modular (through the use of Masks and Adjustment Layers) allowing me to easily change and adjust many different properties of the textures: Albedo, Normal and SRM (Specular, Roughness and Metallic channel packed texture).
More details on the "Books" master material here: https://www.artstation.com/artwork/VrO54