Blond-haired girl wearing a bicycle helmet, a black t-shirt that reads 'Twizzlers' and a printed dog tag necklace around her neck.
a girl with a helmet wears a dog tag
The fact that the girl is wearing a dog tag necklace implies that she also wears a dog tag.
Blond-haired girl is a type of girl, and printed dog tag necklace is a type of dog tag.
If the dog tag is around her neck, she's wearing it.