Yes, there are multiple ways to scale props/ragdolls in Gmod's magic Lua, but so far it can only be done properly with simple props (such as the crate in that screenshot), and with ragdolls only the width of the reference model can be scaled, but not the height or hitboxes. (although there may have been some crazy addon that I haven't seen that allows for this)
Like you said, there will probably have to be another set of models made, but as Kraid said, it's not that important right now as the devs are trying to get the core game finished before they start working on all the extras that ge64 came with.