This is the event text from the Pokemon company
Coming Soon
December 19, 2024 - January 5, 2025
Coming Soon: Shiny Rayquaza Appears!
Tera Raid Battles
Mass Outbreaks
Get Ready for a Series of Events Featuring Special Tera Raid Battles and Mass Outbreaks!
Shiny Rayquaza will be appearing in a special Tera Raid Battle event! And that’s not all—mass outbreak events and other Tera Raid Battle events will occur both before and during Shiny Rayquaza’s Pokémon Scarlet and Pokémon Violet debut. Get an overview of this special event series below.
So the real question is which level they will be at but I know from the text the event will last from Today, 2024 - January 5, 2025, I don't know how it works this will work and what level will it be who is experienced with this event please help