Which is what the US seems to be attempting to do. The president does, under the law, have fairly broad powers when it comes to foreign nations.
With no clear rules set around the issue I don't trust the president to do random judging.
to single company? how about all the other platforms owned by Chinese companies? League of Legends or the like?
This already exists in the form of the World Trade Organization (WTO) and China already flouts those rules. Your plan has been tried and does not work.
So why don’t we sanction the whole country then? Why single out this one app?