Huh, the paper cites World Bank, but WB themselves report differently:

https://data.worldbank.org/indicator/NY.GDP.MKTP.CD

Any other official sources would tell you that US is the largest economy in the world by GDP, which is the most commonly accepted metric.

I don't know where that site is pulling their data from, but not even the Chinese government claims their GDP is as high as that. And our GDP is higher than that site claims

This is Purchase Power Parity GDP (as indicated by the subtitle "This data is adjusted for inflation and differences in the cost of living between countries.")