5  coord()

library(ggplot2)

ggplot(mpg)+
  geom_bar(aes(manufacturer))+
  coord_flip()

ggplot(mpg)+
  geom_bar(aes(manufacturer))+
  coord_fixed(ratio=3/2)

ggplot(mpg)+
  geom_bar(aes(manufacturer))+
  coord_polar(theta="x")