Money doesn't have to come from anywhere - see the record levels of corporate UBI that have been handed out in the form of quantitative easing for the last few decades, PPP 'loans', and tax hacks formatted to save these entities money. There isn't some bag that money comes out of and once you run out of it it's all gone.
There are certainly consequences to be paid when you do that, but so far we seem fine with those consequences when they benefit the most powerful among us.
Its willed into being by the government, like any other money in a fiat money system.
If you are asking what will be done to offset the monetary effects of the additional government spending, then “increased high-end taxes, starting with taxing long-term capital gains the same as other income”.
If you are appealing to the myth of necessary fiscal balance in government operations, well, that’s a myth, but same answer as the monetary answer, to the extent anything is done.
> “increased high-end taxes, starting with taxing long-term capital gains the same as other income”.
This, plus finding a way to make people update their cost basis (and pay capital gains taxes) on property that they want to use as collateral for debt.
There are certainly consequences to be paid when you do that, but so far we seem fine with those consequences when they benefit the most powerful among us.