With lattice plotting functions, use scales=list(cex=1.5)
to set cex
for tick labels along both axes.
To specify different cex
values for x- and y- axes, do something like this:
library(lattice)
xyplot(mpg~disp, data=mtcars,
scales=list(tck=c(1,0), x=list(cex=1.2), y=list(cex=1.5)))