So far that hasn't even happened yet as near as I can tell.
So far the US has bought pesos in the open market to support the currency. Unless the seller is the Argetine government, they do not get that dollars directly. Instead they just benefit from the support of their currency.
The US is also talking about buying $20 billion directly from the government (the aforementioned swap), but Trump says that is contingent on Milei's party winning the upcoming election.
Finally, Bessent talked about getting third parties to also do a $20 billion swap with the government.