Because Barbie is a total fashionista, she perfectly combines a striped halter dress with a polka dot headband ... wears the doll's classic rainbow-striped shirt in a glimpse from the trailer.

The "Levitating” singer, 27, arrived at the Barbie premiere ... 56th Birthday in Sheer Sequin Dress and Radiant Glam JoJo Siwa Shaves Sides of Her Head, Debuts Rainbow Mohawk at GLAAD Media ...