Does classical dance have to be done in hanbok

No. The costumes used in classical dance are not only not limited to Hanbok, but even not limited to classical costumes.

Classical dance originates from classical materials such as opera and martial arts, forming a special kind of classical style dance, but since it has become a kind of dance, it is not limited to classical themes, but it can be applied to the content of almost all the themes, such as modern folk fan dance, jasmine, fishermen's children's love and so on, all of which can be performed in the form of classical dance.