There are no special dorms for young students, at Chicago or anywhere else you are applying. Whoever suggested that in another thread had no idea what he or she was talking about.
If you enroll at Chicago, you will be asked to rank a few dorm choices, and also to answer some questions about what’s important to you in a dorm. Then you may or may not get one of your preferred dorms. You may be “forced” into a dorm you didn’t choose, but it won’t have anything to do with your age, nationality, or anything like that. It will mainly turn on when you committed to Chicago, and which dorms are most popular.
Chicago has been tearing down or selling old dorms and building new ones for the past 15 years, and has plans to keep doing that, so year-to-year there are often changes in the stock of rooms available. There are definitely dorms that are more attractive than others. In recent years, some students have had to be placed in buildings that no one thinks are optimal, but they’re available, and they work OK. It’s not worth worrying about.