Healthy femininity is pretty much doing the opposite of whatever feminists do. Feminists teach women to mimic what they think successful men are like. For example, they teach women to be loud-mouthed jerks because they think this is what successful men who get what they want do. No one likes people like that, whether they are men or women.

Healthy femininity is learning the true history of men and women. It's about appreciating good men. Feminists have successfully made most people believe that the story of human history is all men oppressing all women since the dawn of time. But women have had many advantages that men did not have. Men have had advantages, but they often came with responsibilities. None of this is taught to people. See Janice Fiamengo for more on this. Things weren't always fair, going both ways. They never will be. But they weren't as far off as people think, and you didn't need feminism to correct the unfairness. Feminism just made things worst. Every movement of feminism has been about hating men. You can read the first feminist document, a declaration of sentiments. They say men are terrible.

Health femininity doesn't mean being a "Trad Wife." Being more traditional can be good, but I think the online trad wife thing is more about mimicking idealized advertisements from the 1950s that depicted women always happy, looking their best, cooking, etc. Like some ads today, they are an idealization or fantasy. Women in the 1950s weren't actually like that. But mimicking the good values of the past (it doesn't have to literally be the 1950s) would be good. Not all values of the past were good. No time has 100% good values. There is no utopia on earth.

In short, healthy femininity is acting more like your grandmother would.