I want to use it differently by slightly changing the color of the material of A.
If you try to apply it differently to the sphere on the right,
The material and color of A change as well.
Questions)
What if, after duplicating the color of A, you want to use a different material by changing the color slightly?
I would be very grateful if you could teach me how
Click this button and a new material is created that is a copy of the current material and you can change it however you want.
If you want to re-use the same material but just have color variations, you can adapt the material to use Color Attributes (Either from Vertex Paint or Geometry Nodes Attributes.)
e.g. (2 Cubes using same material and GN Color Attribute here):