Okay, this is a bad take. I’m sorry, it just is. Of course the writers dictate what happens in the story, but we are not going off of the thoughts that we will never know. We are discussing this based on what existing information we have. We don’t know what the Darkhold will teach Wanda. We don’t know how much her powers grew after reading it. We are only going by what information is available, which is what Wanda showed from Age of Ultron to WandaVsion. Based on that information is how I am making my analysis. You mentioning Jean dying in the comics has no bearing on the conclusion to this discussion. The result still remains, since MCU Wanda has never generated enough power equating to a planetary level emp. Nor has she ever directed her powers so finedly to target the inner workings of someone else’s body like Xorn did.
And onto the point you made regarding Xorn vs Phoenix, I’m baffled that it makes sense to you that a planetary grade electromagnetic attack would kill someone who has been inside stars and eaten them, escaping the resulting supernova unscathed, which destroyed the star system it inhabited.
I am not saying Phoenix is invincible, so mentioning such is not only baffling, it is irrelevant.