To use that tool, create your customizations, download the JSON file for your theme, and use e_theme_custom("name_of_my_theme") to add it to a plot. You can also tweak a theme right in your graph ...

The graph above has the Middlesex label above the point and the Fake label below, so there’s no risk of overlap. Scatter plot with ggrepel labels and arrows. And you can use ggrepel to label ...