I work in levered hedge fund strategies, so I have some insight here, although I don't negotiate financing myself. Banks tailor leverage to your strategy, so if your strategy is just to go long good stocks you won't get anything like 6X leverage. 6X leverage is realistic for a strategy that is long and short equal dollar amounts, and also carefully controls other risks besides dollar exposures.

Also, you have to be fairly big to get that kind of leverage. $100 million is probably too small but $1B might be enough.

So you put up $1B of your own money, and a bank would let you go long $3B and short $3B. The idea is that your longs hedge your shorts well so you can't lose too much.

Obviously, in the case of Archegos the shorts didn't hedge the longs well.