Aliens didn’t exactly break new ground in strong female characters (except perhaps with Ripley as lead), but it was an early very popular movie that had strong female characters who weren’t dependent upon men to save them so it was pretty good for representing women as something other than Hollywood’s standard of the time. Not great mind you because the only way either of them managed to achieve that is by making both of them (especially Vasquez, Ripley at least had some nuance) act like traditional male characters, but it was a big step.