Millie, 21, has long been vocal been about how much she wants to portray Britney, 43, describing it as her 'dream role' before the tell-all biopic was even announced.
Millie Bobby Brown politely has clapped back at trolls commenting on her looks.
The actress, 21, has adopted a sultry new blonde hair style that some fans say makes her look much older .
The English actress was in Madrid attending the European premiere of her new film The Electric State, from the directors and writers of Avengers: Endgame.
The siblings left the world premiere of the 21-year-old former child star's new film The Electric State for a family dinner at Italian restaurant Mother Wolf on Monday night
Now, in her latest Instagram posts, the British actress - who has been promoting new film The Electric State - slipped into fun and flirty looks calling back to the Y2K era.