From what I remember, though someone can correct me if I'm wrong, Bumblebee and Aquaman shared IMAX, with Bumblebee in the afternoon and Aquaman in the evening. Maybe that's something they'll do? Or I guess Spider-Man will just five days of IMAX play? Warner has a stronger deal/advantage in IMAX play after all, so it does kind of make sense.
This is one of those moments where I'm really glad I'm not a theater owner, because this Christmas reeks of 2018, when Spider-Verse, Mortal Engines, Poppins, Aquaman, and Bumblebee were all trying to scramble to get IMAX and PLFs from one another. Sing 2 and King's Man will probably try and get into the Dolby/RPX fight this season, so things will get tricky.