Yup. She's one of the strongest in the series, basically if you don't set your party up to negate damage you're done. In that fight, there are actually two ways to win - the most common is once you take away a small portion of her HP (like 30%) her mask breaks and then she really gets OP. If you lose after her mask breaks, you can still continue the game onwards. You *can* beat her, but it requires basically breaking the game's battle system to do it. And if you do beat her, in the next cutscene she just gets up and shrugs it off lmao.