QQQ is security that tracks the NASDAQ (NASDAQ 1% up = QQQ 1% up). TQQQ is a security that tracks the NASDAQ x3. (NASDAQ 1% up = TQQQ 3% up). SQQQ is a security that tracks the NASDAQ Inverse x3. (NASDAQ 1% up = SQQQ 3% down).

In the context of "using leverage to provide better than expected returns in a Bull market", someone can buy TQQQ, securitize/create derivative (this is exclusively what crypto does) that returns 1.5 times the NASDAQ, sell you that derivative, and if the NASDAQ goes up 5% (TQQQ 15%) you get 7.5% and they get 7.5% (and your money).

If it goes down, you lose everything and they keep the money you gave them.