Jacques-Louis David was an influential French painter during the Neo-classical period of Art, his style was considered to be the most ahead of its time. he painted royalty being crowned, the infamous Napoleon riding his horse. Looking at his paintings you can see how he used fashion in a new unique way that had never been seen before, making the paintings more dynamic and life like.
You can see the influence of the classical type of painting but with a new twist, which is why they named the period Neo-Classical, which Jacques-Louis was at the forefront.
In terms of a fashion expect, this is where we begin to see the change in how its portrayed in pictures, its used in more dramatic ways. Emphasising pictures or making them impactful, as you can see in the crowning ceremony picture he painted. You see a lot of this used in todays fashion pictures, not in this exact way but as an inspiration point.