I would think that all you have to do is divide the part’s size to make it the correct scale, and CFrame it to the new proper position based on the size of the wolf’s head.
local newScale=0.8 --reduced to 80% size
part.Size=part.Size*newScale --rescale the part
part.CFrame=wolf.Head+Vector3.new(0,wolf.Head.Size/2,0) --the part's position based
-- on the size of the wolf's head