In the sci-fi novels and films I have read or seen, there's a variety of roles women play. I have seen both in-depth, complex characters, like Lieutenant Nyota Uhura of Star Trek or Ripley of Alien, and helpless victims, excessively sexualized, like Scarlet Witch, Ms. Marvel, and many other women from the (typically older) Marvel Comics, and in Star Wars, though in this latest movie, they did a better job at removing sexual stereotypes from the women, with Rey and Captain Phasma. These characters likely vary based on the author's decision - if a male author understands women struggle with oversexualization, he will likely write female characters with more depth and less sexualization. If an author is unaware of this sexualization, or believes
