I respectfully disagree. A bigger GDP would mean more military spending per percentage of GDP. America would need to increase its defence spending to maintain its lead over China.
There is a double standard when it comes to GDP, PPP and defence spending comparisons
The US naturally wants to use nominal GDP numbers for GDP because if PPP was used China's GDP would dwarf the US, however, both Chinese and American defence expenditures are almost entirely spent domestically which would mean PPP figures are a much better basis of comparison, it also helps the hawks in the US bump up the value of the Chinese defence budget by 33%, but to do that would mean to tacitly admit they aren't the biggest economy in the World and China has already over taken them, which is political taboo!
Besides as things stand the US spends over 2 times what China spends on defence, on a percentage of nominal GDP basis so plenty of room to grow and here's the rub if China was to spend the same proportion of its GDP as the US on defence, at PPP, it would actually be about 40 billion USD more than the US.
The 'fight' may already be lost it just serves the interests of both sides not to talk about it!
Therefore like so many things in the world of today, Joe 'not on my watch' Biden's administration will just carry on with the see no evil, hear no evil, speak no evil fudging!