It's kind of a question of where you draw the boundaries. Chongqing counts ~30M because its administrative area is the size of Austria. The UN World Urbanization Prospects project [0] tries to establish comparability between nations, and came up with a top 10 of:
1. Tokyo - 37M
2. Delhi - 29M
3. Shanghai - 26M
4. São Paulo - 22M
5. Mexico City - 22M
6. Cairo - 20M
7. Mumbai - 20M
8. Beijing - 20M
9. Dhaka - 20M
10. Osaka - 19M
NYC is next at #11 with 19M.
However, if you count strictly by "city proper" (as defined by a very wide range of administrative agglomerations), there are indeed THIRTEEN cities in China larger than NYC. I'm not sure this is a hugely useful metric, however, as economically-relevant city boundaries aren't truly represented by administrative lines of control.
1. Tokyo - 37M
2. Delhi - 29M
3. Shanghai - 26M
4. São Paulo - 22M
5. Mexico City - 22M
6. Cairo - 20M
7. Mumbai - 20M
8. Beijing - 20M
9. Dhaka - 20M
10. Osaka - 19M
NYC is next at #11 with 19M.
However, if you count strictly by "city proper" (as defined by a very wide range of administrative agglomerations), there are indeed THIRTEEN cities in China larger than NYC. I'm not sure this is a hugely useful metric, however, as economically-relevant city boundaries aren't truly represented by administrative lines of control.
[0]: https://population.un.org/wup/Publications/Files/WUP2018-Hig...