Portrait of Tsarevich Pavel Petrovich in the admiral’s uniform Nicola-Benjamin Delapierre (1739-1800)

The picture has something of this: people, woman, wear, portrait, girl, sword, two, man, veil, costume, dress, snake, pants, model.
Perhaps it’s a painting of a man in a blue and white outfit with a sword in one hand and a snake in the other.