I would think that most people reading historical fiction are expecting some level of unpleasantness in the setting. It comes with the genre. If someone didn’t want to deal with that at all, they’d read a contemporary or fantasy story. So I think it’s fair to trust that the audience knows what they are getting into, especially if you add a warning/explanation in your post.
Might be worth mentioning another WIP set in Roman Times, Defiled Hearts. There’s slavery, colonization, xenophobia, and misogyny in the game, and the experiences and romances of the MC does change based on their selected gender (ex. AFAB MCs have to pretend to be AMAB). It doesn’t go into detail with these topics and (imo) the world-building would be improved by doing so, but you could use it as a baseline for what is acceptable to readers.