We will never know....
Because there is no ACTUAL Free Trade.
If on the one hand, countries with lower wage rates are allowed to simply sell their wares here with no restrictions or obligatory regulatory oversight, and on the other hand, US producers must pay much higher wages, comply with far more regulation than the foreign competition, and pay a higher taxation rate than that assessed in the foreign country, then of course there is a distinct tilt to the playing field.
And that is not “free trade” at all. All the trade goes from the country with the lower costs of production to the country with the higher costs of production, and there is no reciprocity.