Well, I made a Giant kobold, then made myself into one, and managed to shove a small female kobold into the rear of giant female kobold. Fell through belly instantly. BEWARE Apparently all your Assets are grown when you do that. You can become too big to fit into the house within 10 secs or so, if you put into the grinder, Melon + Eggplant + HEart X 2 and let the Kobold or PC stand in the Full spray of the compound. Only way I managed to get into the house was to Crouch. Also the physics is the lower jaw is overlapping the screen constantly when at that size.
It is a breakable body physics, looks a complete mess if you sex your kobold at mass size ( not you ) in the house, I havn't tried outside yet. When you and the Kobold ( Female ) are both massive size, Sex option does not appear. You have to do it manually.