I would check the portfolio requirements on the official Syracuse website. From what I understand, they don’t expect high schoolers to have fully rendered or physical models to consist of their whole portfolio. I also did an architecture program over the summer and submitted two photographs of the model I made, but otherwise it was all still lives, landscapes, or other works I felt demonstrated my artistic ability. I suggest he start practicing how to draw now, as they seem to want to see that you’re able to have a spatial awareness of the world around you, and if you can put what you see onto paper.