Infanta Isabelle de Bourbon-Parme (1741-1763) Jean Marc Nattier

The picture has something of this: child, people, dress, princess, baby, wear, portrait, girl, crown, woman, costume, beautiful, theater, retro, dancing.
Perhaps it’s a painting of a young girl in a white dress with gold trim and a tiara, standing in front of a blue curtain with a bridge in the background.