As a Chinese person, I guarantee that nobody really cares. China’s high population is seen as a fun fact and an interesting thing to talk about at best and, if the attempts at the one-child policy is a hint, considered a disadvantage at worst, at least before the OCP was abolished. I don’t know much about India’s thoughts on this but I can’t imagine they’re banking that hard on population for their national pride. Someone is bound to have the highest population and being that country doesn’t make you special in any way that actually matters.