As far as I know there are only UpVector, LookVector and RightVector, I am pretty sure they only made this many because you could just get the opposite of it and it will give you all the directions, but how would you that? I tried using CFrame:Inverse, but have no Idea how to use it here is what I came up which outputted something I did not want.
local part = game.Workspace.Part
local UpVector = part.CFrame.UpVector.Unit
print(UpVector) -- 0,1,0
local DownVector = part.CFrame:Inverse(part.CFrame.UpVector.Unit)
print(DownVector) -- Outputed --> 1.20000005, -0.749998987, -77.1999969, 1, 0, 0, 0, 1, 0, 0, 0, 1 which is not what I wanted Desired Output --> 0, -1, 0

3 comments
Firstly, all the directional Vectors are already in Unit format, secondly, CFrame inversion doesn't correlate to what you believe it does in this context. Lastly, to get the reversed direction, simply give it a negative sign.
@Zifixture I did not know you could put a negative sign, ty.
Just like Position or size, you can have negatives