https://cran.r-project.org/web/packages/ggfittext/vignettes/introduction-to-ggfittext.html

Sometimes you want to draw some text in a ggplot2 plot so that it fits inside a defined area. It’s possible to achieve this by manually fiddling with the font size, but this is both tedious and un-reproducible. ggfittext provides a geom called geom_fit_text() that automatically resizes text to fit inside a box. It works like this: