As I already mentioned above, Paris achieves it's density mostly through low rise density.
The majority of Paris looks like this, but more middle class.
Paris has over 2.1 million people. It turns out these buildings can house them just fine.
Economists generally agree that building much more housing both lowers rents and meets demand: https://www.upjohn.org/research-highlights/new-apartment-buildings-low-income-ar...
Banlieues tend to exist in suburbs of cities in France. That's a strike against suburbs and for cities.