Optimal city placement (OCP) won't get you a ton of cities.
OCP tries to cover as much territory with the least amount of cities. The theory behind this is with fewer cities you would have less corruption.
To get hundreds of cities, play on a huge map (preferably pangea) and place cities all over the place (dense build), not caring about overlapping other cities. In my current game, the domination limit is 3700+ tiles. You can build a maximum of 512 cities, so that is about 7 tiles/city.
Even though corruption is high, you can actually produce more with a dense build. With a dense build I very rarely not have the game won before hospitals and factories become available.