As you know from the start of march we can use R in power BI. In R  Exist a specific library to create custom chart that we can use in Power BI called GGPlot. For example we can create a chart like this:

I found online this 2 very interesting course about ggplot:

Data Visualization GGPlot Course 1

Data Visualization GGPlot Course 2

An example that you can learn with these two courses:

• Chapter 1: Learn how to use ggplot2 as a tool for graphical data analysis by applying a variety of statistical methods.

• Chapter 2: Get to know the Coordinates and Facets layers to make your plots easier to read and understand.

• Chapter 3: Learn all about adding and adapting themes to make publication quality plots directly in R.

• Chapter 4: Discover the best and worst types of visualizations for particular scenarios to make your message as clear as possible.

• Chapter 5: Combine everything you’ve learned in a step-by-step case study. Using real data, you develop mosaic plots by combining statistics and flexible visuals