Let's take some other anti-social behaviour as an analogy. Imagine person A is in their car, idling their engine, outside an elementary school at pick-up time[1]. Now imagine person B comes up and asks them to stop. How well do you think that works if person B gets out of a car which is also idling its engine when they come and make the request?
Your argument seems to be that person B's car is smaller. I don't think that helps much, but it's also not in any meaningful way true. China's emissions are large only because China is large. Per-capita emissions are what matter here (otherwise it would solve the problem of China being a large emitter if China were to split itself into a dozen smaller countries — which is clearly nonsensical). China's per-capita emissions are less than half those of the US[2], and some of them are emitted in producing goods for export to the US.
[1] I live opposite an elementary school, and this is sadly not unusual.
China’s Greenhouse Gas Emissions Exceeded the Developed World: https://rhg.com/research/chinas-emissions-surpass-developed-...