Fonts

plot(1:5, xlim = c(0, 6), ylim = c(0,6), 
     xaxt = 'n', yaxt = 'n',
     xlab = 'xlab font = 5', ylab = 'ylab font = 5',
     font.lab = 5,
     main = 'Main title font = 3', font.main = 3,
     sub = 'subtitle font = 4', font.sub = 4)
axis(side=1, at=1:5, labels = rep('font=4', 5), font.axis = 4)
axis(side=2, at=1:5, labels = rep('font=5', 5), font.axis = 5)
labels = paste0('font=', 1:5, '; family=serif')
text(x=1:5, y=1:5 + 0.5, labels = labels, 
     font = 1:5, family = "serif")