A question about the Index LN?

No. It's said that Aleister was the greatest magician in history but not the most powerful magician in history. Aleister has done a lot to further magic for all magic users by combing it with technology. His research have completely expanded the horizons, but Aleister himself isn't extremely powerful. If he went one-on-one with Othinus, Aleister would completely lose. Othinus is a Majin because she is the most powerful magic user that's currently alive.