I don't know who this lovely lady is but her outfit is perfect! You can never go wrong with baggy tops over tights or leggings. The key to achieving this look is keeping colours neutral, accessories minimal, and being comfortable - the effortlessness of this look starts with you!
Charles James (American, born Great Britain, 1906–1978). "Swan" Evening Dress, ca. 1954. The Metropolitan Museum of Art, New York. Brooklyn Museum Costume Collection at The Metropolitan Museum of Art, Gift of the Brooklyn Museum, 2009 (2009.300.8523) #CharlesJames