Yaxis different than Ylim : Is it possible ?

Could you elaborate a little more in your question? ideally, could you ask this with a minimal REPRoducible EXample (reprex)?

If I'm understanding you correctly I think you can get what you want quite easily by using ggplot2


df <- data.frame(x = sample(1:100, 10),
                 y = sample(1:100, 10))

ggplot(df, aes(x, y)) +
    geom_point() +
    scale_y_continuous(limits = c(0, 100)) +
    labs(title = "Sample Plot",
         subtitle = "Here you can write all the text you want\nwithout interfering with the y-axis")

Created on 2019-10-02 by the reprex package (v0.3.0.9000)