Portrait of an unknown man in a purple caftan Vladimir Borovikovsky (1757-1825)

The picture has something of this: people, portrait, wear, man, exploration, leader, jacket, scientist, outerwear, neckwear, music, light, retro, writer, mustache.
Perhaps it’s a painting of a man sitting at a desk holding a piece of paper in one hand and a book in the other hand, in front of him.