Le Chevalier d’Éon by Angelika Kauffmann

This is a painting that many other paintings of d’Eon are based on. It was painted probably in or about 1775 when d’Eon was 48 years old. Possibly (probably) later. I have not yet found a proper date, just Wikipedia, but as Kaufmann was born in 1741 it could not have been painted at the age d’Eon appears.