This whole site is dedicated to 3D models as used in video games or possibly by a 3D plastic extrusion printer.
https://free3d.com/3d-models/all
I have found that the .obj files will open in 3D Builder (included with Win10) and a .DFX file will open in Libre Office, if that's of any help.
There may be a way that they can be opened in Blender or other such 3D rendering programs, then exported into pepakura designer, then unfolded to a .pdo ... but such things are way outside of my skills range. I've bookmarked the page as there's some very interesting stuff on there. Especially the birds.
I know that there are people out there that regularly extract figures from video games and through methods unknown to me, insert them into pepakura for unfolding. I'd love to get to know how to do this myself, so I'll be monitoring this thread closely to see if any of our more skilled designers can offer any further help on the subject.