best defi platforms for collateralized margin trading?

i've been using morpho, where you can get up to 9x, but just saw this article referencing a whale getting up to 40x: https://cointelegraph.com/news/ethereum-whale-opens-16-3m-long-as-eth-price-eyes-bounce
how? where?
thanks!
submitted by /u/ThenOwl9
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