For a more modern visual design, consider adding monochrome images to your courses. These images are stark, sometimes overexposed (meaning lots of white and a loss of details), and typically black and white.
They don’t have to be just black and white though. Sometimes a pop of color is intriguing. If you have the capability, you can add the pop of color yourself and have it match a primary color of your course.
Monochrome visual design doesn’t always have to be black and white either. It really just means a single color. This could be a cool blue color. Sometimes, it is also sepia (tan/yellow). Other times, it might be shades of brown or green.