To use Material Variants, you must be working in Unity 2022.1 or above.
Material Variants are compatible with existing materials. To create a variant of an existing material, go to your Project window, right-click on the Material Asset and choose Create > Material Variant. You can also convert an existing material into a Material Variant. This is useful if you already have duplicate materials and want to reparent them to a common parent material with the new workflow in your project.
Additionally, you can lock some properties in the parent material to prevent the child material from modifying them (i.e., Surface Options), modify properties in the child that won’t affect the parent material (i.e., Base Map color), and modify the parent to apply some changes that need to be applied to all children materials (i.e., a new Base Map texture).
At any point, you can check the Material Variant hierarchy to verify the impact of changes made at any level or that you’re making changes at the right level of the hierarchy. Material Variants offer plenty of useful functionalities like reparenting, reverting, or applying overrides upward. To learn more, read our documentation here.
Source: Unity Technologies Blog