Nope, Congress has authorized the executive to impose tariffs multiple times for multiple different reasons. Tariff Act of '30, Trade Expansion Act of '62, Trade Act of '74, etc.
A situation where a corrupt and incompetent president is explicitly trying to blow up the US economy using not-really-relevant laws as a pretext was not ever anticipated, and he will hopefully be strongly rebuked (e.g. impeached) by the next Congress.
Your comment begins "Nope, Congress has authorized ..." which just supports the point of the GP that it is Congress that controls the setting of tariffs, even if that may sometimes mean delegating it to the executive branch.