> Now Iran knows they can blockade that Strait and makes these demands so they have much more leverage
Tehran has more potential leverage inasmuch as they've credibly demonstrated they can block the Strait. Whether they have more actual leverage than before is uncertain–trade flows are routing around them. And their own shores remain blockaded. (Just because the U.S. has less leverage than it did before doesn't mean Iran necessarily has more.)
They can make all the demands they want. I can demand you give me a thousand bitcoin to not burn your house down. That doesn't mean it has any remote chance of happening.
Tehran has more potential leverage inasmuch as they've credibly demonstrated they can block the Strait. Whether they have more actual leverage than before is uncertain–trade flows are routing around them. And their own shores remain blockaded. (Just because the U.S. has less leverage than it did before doesn't mean Iran necessarily has more.)