https://www.google.com/covid19-map/?hl=es-EC
Google created a map to track COVID-19 cases reported around the world. It uses color with different levels of darkness to highlight countries with the most number of cases. Interactive tools such as a hovering capability allows you to see more information on the specific country.
I think color was used successfully because it does not overwhelm the reader since it only uses blue in different shades. You also have a dropdown menu to filter information by country and a timeline towards the end of the page that shows the cases in the past months.