3D modelling can be very time consuming, I have done some simple modelling for my own projects, but not yet completed anything for a jam, I recently tried to make a 3D game for the recent underwater horror jam, but missed the deadline.
If you want to make a 3D jam game, you might have to work on your own assets over time and then use some of them in a jam in future.
I have found that making 3D assets and a game in short time frame is quite difficult if you want to include more than basic shapes or a basic game.
Good luck with the jam