the Theme

minimal_plus = theme_minimal() +
  theme(panel.grid.minor = element_blank(),
        panel.grid.major = element_blank(),
        text = element_text(color='#818181'),
        plot.title = ggtext::element_markdown(size = 20, color="#535353"),
        plot.subtitle = ggtext::element_markdown(size = 16))

Sample Plot

ggplot(data=cars) +
  geom_point(aes(x=speed, y=dist)) +
  labs(title="This is a plot of <span style='color:#233F7D'>**the cars dataset**<span>",
       subtitle="along with a subtitle for demonstrating *markdown*")+
  minimal_plus