AskHistorians

Also, Napoleon commissioned several portrait artists based on their skills, not association. A few portraits of Napoleon including one by Paul Delaroche is noted for its portrayal of a defeated, human-sized, and "short" Napoleon. There was even a portrait artist by the name of Élisabeth Vigée Le Brun who chose to live in exile rather than paint the Emperor.

Point being, artists that didn’t like Napoleon often took the money, churned out slop, and I believe tried to make him look tiny and weak.