Did the law give Trump the power to change the deadline through executive order?

Yes, it does, but only a one-time 90 day extension and only if the President says there is concrete progress toward a sale to a US entity. Of course, this President will say anything that benefits him personally, whether or not it is true. So he says the magic words, and all interested parties (Bytedance, Zuckerberg, Musk, etc.) continue to buy his shitty NFTs and tokens to influence his decisions.