It is possible but with some limitations. A giant can be so big that it is outside the draw distance making only the legs visible. There is ways around this but then the problem is framerate. So yes it is possible in some scenarios. Depends on what kind of scene it is in.
I'm a fan of the super huge one that breaks the bridge during the old highway level. She served as a little scripted cutscene element and only existed for a small amount of time so she wasn't super taxing on the game.
your game is amazin how is the next to update and please contac me to date of update you can add store in the game when you play recieve coins and whit coins buys gigantess?