Much of the debate around the twin towers falling was the effects of how hot jet fuel can burn and its effect on the steel structure, with engineers concluding while it wouldnt melt, it would weaken the already damaged structure enough for it to collapse.
But again, no planes hit Tower 7, there was no jet fuel, and no damaged structure, making it a skyscraper collapsing purely by fire, which has never happened in the history of skyscraper fires.