I can't really see how you approach that debate, particularly with this age group, without doing harm. Assuming it's a mixed group, this forces girls to either sit and listen to their classmates arguing to remove their rights or forces girls to argue for the removal of their own rights if they're put on the 'for' team.
In any event, I doubt this age group has the historical or real-world knowledge to argue this meaningfully anyway. Of course we should discuss it, but I'm not sure a debate setup is the right way to do it. It's certainly not a forgone conclusion that the kids will come away having been educated on sexism- that may not be the outcome at all.
We were organised to debate abortion rights at school and a girl assigned to the team arguing against abortion rights was an exceptional debater. I have no idea whether her true opinions aligned with her position, but to a group of teenagers without the contextual knowledge to understand why the right to a safe abortion is so important- she was convincing. For a group of kids without enough life experience to understand the implications of the discussion or a reasonable understanding of the history, the pendulum may well swing the other way, at least for some of them.
In my experience as someone who used to teach PSHE, any discussions of this type need to be carefully managed- ESPECIALLY when they relate to a protected characteristic. Open the floor to any and all contributions where students are encouraged to argue against a group's lawful rights, and the whole thing can take on a life of its own and get out of control quite rapidly!