https://ggplot2-book.org/index.html

10 Position scales and axes
11 Colour scales and legends
12 Other aesthetics
13 Mastering the grammar
14 Build a plot layer by layer
15 Scales and guides
16 Coordinate systems
17 Faceting
18 Themes
19 Programming with ggplot2
20 ggplot2 internals
21 Writing ggplot2 extensions
22 Case Study: Springs
Reference
[Book]ggplot2: Elegant Graphics for Data Analysis by Hadley Wickham https://ggplot2-book.org/index.html