That’s a different question. The person you’re replying to was referring to historical totals and they were right:

https://ourworldindata.org/contributed-most-global-co2

> the United States has emitted more CO2 than any other country to date: at around 400 billion tonnes since 1751, it is responsible for 25% of historical emissions; this is twice more than China – the world’s second-largest national contributor