Such as all the costume changes for Beyonce in a concert...
In English 'fantasy' can be anything that is not based on real life. A fantasy costume. A fantasy book. A fantasy game.
Bro, we think of fantasy as "not reality" or an illusion someone imagines, not unusual clothing. For unusual clothing we could say costume (pretending clothing) regalia (special clothes for something like a ceremony) or uniform (clothing specific to a job, school, military, or an organization)
I think [but really... I'm not a Brazilian genius] that costume is intended as masquerade...
She is wearing a costume =
- Ela está a vestir uma fantasia (EU PT)
- Ela está vestindo uma fantasia (BR PT)
So does 'Ela veste uma fantasia' mean that she (usually/normally) wears a costume, rather than that she is wearing one now?
She wears a costume... to the ball.
She wears a costume... at work.
What does she do for her job at Disneyland? She wears a costume.
This exercise is a "Simple Present" one not a "Present Continuous" one.