You cannot have significantly more people/square meter with everything else remaining equal. Cities are like stars - quantitative change in density causes qualitative change in behavior.

Once you have density high enough you can't live in separate houses. People move to commieblocks or other kinds of multitenant buildings. This shifts everything closer together, makes public transport profitable and having a car becomes optional. These kinds of neighborhoods are quieter than the countryside usually. It looks like this: https://spoldzielnialsm.pl/wp-content/uploads/2018/05/Obecni... https://4.bp.blogspot.com/-ud9-Z0UHVHg/W7-qUjfNT9I/AAAAAAAAi...

Or if you're insane you can mandate enough parking space that this doesn't happen and instead you have highrises in the sea of parking lots.