chapotraphouse

People have full reproductive control. That includes the ability to change sex at will, to control fertility, to pause pregnancies, even to get pregnant, change sex, and go through pregnancy as a man

Beyond what the other reply said, there are also examples of societies that have 3 genders - for example, the people of Azad in The Player of Games have male, female, and apex (I think they do have the tech to change gonads, but would not use them because their society is turbo-sexist. Also CW for all sorts of gender stuff in the Culture series, it's NOT all sunshines and rainbows for the people outside the Culture itself).

Scifi Magic transing is central to the plot of Excession(1997)

From Player of Games:

'I feel you want to take me,' Yay said, 'like a piece, like an area. To be had; to be possessed.' Suddenly she looked very puzzled. 'There's something very I don't know; primitive, perhaps, about you, Gurgeh. You've never changed sex, have you?' He shook his head. 'Or slept with a man?' Another shake. 'I thought so ,' Yay said. 'You're strange, Gurgeh.' She drained her glass.