When she was about 16, Ms. Ponce decided to undergo hormonal treatment and eventually vaginal plastic surgery, “to remove what for me was a burden and a trauma.” But she said that her message to the teenagers whom she now meets is always that vaginal surgery is a personal choice, and that it is not essential to being a woman.

“There are women with a penis and men with a vagina, because the only key part of being a woman is to be and feel like a woman,” she said.

Her recent success as a beauty queen has brought her admirers, but also plenty of attacks — mostly from other women, she said.

“What strikes me is that a lot of the criticism has come from women and people from my own collective, just when women are taking to the streets to ask for recognition,” she said. “I find it weird that some women don’t tolerate that I go to a competition to represent my country as the woman that I am.”

She added: “If we want progress, we just have to stop looking whether what other women are doing is good or not.”

Surprisingly to some, predominantly-Catholic Spain has led the way on several gender-related issues. In June, the country’s new prime minister, Pedro Sánchez, appointed 11 women as the heads of the government’s 17 ministries, the highest proportion among Western countries.