In a costume you can be something other than yourself. The Guardian (2020)

French translation of 'costume'

costume

[ˈkɒstjuːm ]

noun

1.  [of actor] costume m

The cast makes its own costumes. La troupe confectionne ses propres costumes.

2.  (traditional) costume m

3.  (= lady’s suit) tailleur m

4.  (Britain) (also: swimming costume) maillot m ⧫ tenue f de bain

 

Collins French-English Dictionary © by HarperCollins Publishers. All rights reserved.

In French it's called a costume which is much more accurate.

https://teacherpower.org/blogs/blog/dressed-to-teach