There are various ways to set the formatting of labels in plots. First and foremost, you may want to change the label text:
ggplot(data=iris, mapping=aes(x=Sepal.Length, y=Petal.Length, color=Species))+ ggtitle("Iris")+ geom_point()+ gg_("set the x-axis label to 'This is my x-axis'")+ gg_("The y-axis label should be set to 'Welcome to the jungle', please")ggplot(data=iris, mapping=aes(x=Sepal.Length, y=Petal.Length, color=Species))+ ggtitle("Iris")+ geom_point()+ gg_("Rotate the x-axis labels by 32°")+ gg_("Rotate the y-axis labels by 172 degrees")ggplot(data=iris, mapping=aes(x=Sepal.Length, y=Petal.Length, color=Species))+ ggtitle("Iris")+ geom_point()+ gg_("Paint the x-axis label in coral.")+ gg_("The label of the y-axis should appear in purple.")