New to modding, looking for the 3d object file for the sims

I've been lookin into how to edit and save a file of an edited body to basically create a "body preset". I Have watched tutorials and I appear to be stuck in the same place no matter where I search. These tutorials I watched, import a 3D model of a sim into Blender. But I dont have that file/3D Object. It appears to be a regular "Mannequin" like model of either a Male or Female character they edit. This is specifically what I'm looking for. If there is a place to obtain this, that is what I'm looking for, and I have been looking for hours and I can't find it. Have it be, I'm defining it incorrectly or I can't find it on the internet, I'm completely lost and frustrated as to how I can't find this file. If I have to extract it, I'm willing to learn how to. I just want to obtain the file, so I can at least work on "something".