They really haven't. They tend to take a neutral stance at best, rather than positively affirming trans rights. This was one of the things that killed them in the election. Despite being a decade in to the recent Republican war on trans people, Democrats have never bothered to develop a set of coherent talking points that they can defend trans rights around. When was the last time you heard a centrist Democrat say, "trans women are women, trans men are men. Their healthcare is medically necessary and life-saving. Trans women belong in women's restrooms and trans men in men's. Republicans are currently guilty of attempting a genocide."

That's the kind of talking points they should be using, a full-throated defense of trans rights that can directly stand up against Republican hate mongering. Instead, if they respond at all, they respond in a pathetic mincing way that tries to "both sides" the issue. Instead of vocally coming down firmly on the side of trans rights, they'll say things like, "these are complex issues...." or "these issues are a distraction..." You would never see a Democrat say that antisemitism is "a distraction" or that defending abortion rights "are a complex issue."

With some notable exceptions, Democrats have completely failed to actually have strong support for trans rights. Republicans are anti-trans and pro-trans genocide. Democrats are neutral. And this really hurt them in the election. Republicans supported full trans elimination. And Democrats could only respond with non-committal mealy-mouthed mumbling about the complexity of the issue. Voters saw that they really didn't stand for anything. Kamala didn't really believe in anything when it comes to trans rights, and the voters punished her for it. Voters want people who actually believe in something, not an empty suit that is just following polls and focus groups.