Agree with this as a trans woman player + fledgling DM.

I prefer the game to be mature as a two-way street. Violence and sex are present, and sometimes shockingly so, but that’s because we trust each other to recognize the gravity of those topics and handle them like adults. I’m not even 100% against any and all depictions of sexual(ized) violence, but And sure, PCs are people with desires, but in these stories I prefer it to be uncommon for the PCs to even have the time or attention span to start acting habitually hoarney. Sure, there have to be some opportunities to let our hair down but most of the time, the stakes of the game are really high. Crushes and secret flings are more interesting when they occur in pockets between running for our/their lives. And yeah this kind of non-consensual + quasi-necro stuff in combat is just a session 0, not-that-kind-of-game, any immature player needing to be called in situation, that people regularly post about.

I will say that while I agree with commenters saying OP has likely vastly over emphasized the player’s transness as a factor of their behavior… this player does kind of sound like A Type of babytrans trying to live out a second, less traumatic adolescence of a sort, which has been known to produce some obnoxious behaviors, and it may be that their sexuality and newly-found gender euphoria are kind of tangled up at least for now. But that isn’t actually helpful to rectifying this situation - right now it looks like a standard issue “we aren’t in this for murder hoboing (+ etc)” intervention is the first step.