You might have the story twisted.
In reality since the women's sexual liberation women wanted to wear sexy and fit clothes so the clothes produced are fit sized.
Companies just adapt to the demand.
If tomorrow ALL women stop purchasing tight clothes to buy large ones at the men's aisle, all companies would start again producing large clothes. And rn it's actually the case they do offer large clothes.
It's like all the time when women's habits change, companies adapt and double down with ofc aggressive marketing.
(E.g post-victorian era when women started to shave to piss-off the "patriarchy" and the importance of hair on a woman theory (at the time, back then) and so King C. Gillette started to advertize his safety razors to women)
They do try to shape trends but it's hardly manageable. Especially now with the rise of social medias for influence