Because of the way OLED works, it may be worth changing white backgrounds to something darker especially if your commonly used applications or web pages are predominately white. At the most extreme, white at maximum brightness will consume almost 14 W more than if the screen were only black.
https://www.notebookcheck.net/Dell-XPS-15-7590-OLED-Power-Consumption-Measurements-White-Can-Be-Almost-Two-Times-More-Demanding-Than-Other-Colors.430835.0.html