I would say you can not do, depending on what hotel, they stay at.
MK will be extremely busy at 9:30 AM, December 24 on a EM AM day.
The way to do it would be do the EM AM - then leave the park at 10:30 AM or eat breakfast, then leave
and go to another park.
Per the Walt Disney World website
More Time to Enjoy Select Attractions
Each day, Guests staying at select Walt Disney World Resort hotels have the opportunity to enjoy select attractions in at least one of our 4 theme parks, before or after regular operating hours. To see when and where the Extra Magic Hours benefit is offered, view
today’s park hours or consult the printed Times Guide, available at the Disney Resort hotel Front Desk.
Participating Hotels
Extra Magic Hours is a benefit for registered Guests staying at participating Walt Disney World Resort hotels and Official Walt Disney World® Hotels, which include:
Valid theme park admission and hotel ID required.
Participating Attractions
During Extra Magic Hours, select attractions will be open at a park for your enjoyment.
Please note that attractions are subject to change and may not always be operational. To learn about any unplanned closures or long-term refurbishments, please view details about the attraction on our website or mobile app, or refer to the printed Times Guide.
Magic Kingdom Park — Mornings
The following attractions are open during morning Extra Magic Hours at Magic Kingdom park: