How to add a caption/subtitle to corrplot plot (R)

I have produced a corrplot plot that gives correlation between variables. I now simply want to add a subtitle/caption to note things about the variables, at the bottom of the plot. However, because it's not like ggplot, I cannot seem to make the label appear. I have used the argument main = to produce a title, but sub = does not produce anything.

Is it possible to add a subtitle to a corrplot rendering? If not, is there a way to take the corrplot output and put it into another object that would allow me to add a caption/subtitle?

My plot looks like this:

And my code is this:

correlation_plot <- corrplot(corr = cortable, method = "number", main = "Title", sub = "sub", type = "full", number.cex=0.70)

where cortable is a generic dataframe of observations for columns A-E.

Also, is there a way to stop the Title from being cut off at the top? Is that cutoff whats actually preventing me from seeing a subtitle too?

The problem is that corrplot changes the default margins and so cuts off both the title and subtitle.

library(corrplot)
corrplot(cor(iris[,1:4]), main = "title", sub="subtitle")

You can do better, by specifying a margin more like the defaults

corrplot(cor(iris[,1:4]), main = "title", sub="subtitle", mar=c(5,4,4,2))

But to get a really good result, specify a modest margin and then add the title and subtitle separately using title

corrplot(cor(iris[,1:4]), mar=c(1,1,2,1))
title(main="title", sub="subtitle")

Experiment with the margin size to get a placement that looks good for your corrplot.