I don't think Fusion can do exactly what you're after. You would have to change materials manually. You could save versions with different material combinations and switch between them in order to compare but these versions wouldn't incorporate later design changes.
Also if you have multiple parts in an assembly that you always want to keep as the same material (you might want all the bolts to look the same for example), instead of dragging the material to each bolt separately you can drag it over the previous material in the "In This Design" section of the Appearance dialog to change them all at once. Hope that helps.
