Basics: US$ is fed's liability, meaning it doesn't need to pay b

In other words, "Fed prints money,"  as they always say.  It also means, the Fed, unlike anybody else, DOES NOT NEED TO PAY IT BACK.  While for anyone who's not the government, printing money is strictly illegal.

https://www.investopedia.com/articles/economics/10/understanding-the-fed-balance-sheet.asp

In terms of how much it prints:

https://tradingeconomics.com/united-states/central-bank-balance-sheet

If you click on the "5y" button, you can see how in 2020, fed's balance sheet jumpep up vertically.