You’ll find dozens of threads by people completely booked out of their favorite resorts later this yearbecause they waited too late to book. And lots of travel reports the the resorts that have reopened are fully booked and not holding rooms back.
Many resorts have been near sold out for Aug-Dec because of the compilation of the 50th, trips rilled iver from last year, and COVID “revenge travel”. You should expect the resorts and parks to be significantly more crowded this December, maybe even more crowded than this Summer. “Normal” doesn’t apply. Everyone and their brother is splurging and heading to WDW to celebrate getting out if the house.