Does :SetPartCollisionGroup only accept baseparts? not models ?

I heard somewhere that doing :SetPartCollisionGroup on a basepart meant that all it's descendants will also be affected

I used the code

local PhysicsService = game:GetService("PhysicsService")

local Part1 = workspace.Part1
local Part2 = workspace.Part2

wait(5)


PhysicsService:SetPartCollisionGroup(Part1,"Group1")
PhysicsService:SetPartCollisionGroup(Part2,"Group2")

By the way I created an group in an server script so don't worry about that

this is an local script

But What I thought it would do was if I put any one of them in an group all it's descendants will also follow the collision rules