Size of plot produced by corrplot

Is there any way to increase the overall size of the plot produce by corrplot?

For example, if I plot the correlations of all 61 columns of the volcano dataset

library(corrplot)
M <- cor(volcano)
corrplot(M, order = "hclust", addrect = 2)

the plot is unreadable because the overall size does not increase. I am on Windows 10, corrplot 0.84, Jupyter notebook, making calls to R 3.5.1 using the magic R command %%R. But I have also run this in RStudio and have the same problem.

I have tried increasing the plot size with

 win.graph(width = 20, height = 20, pointsize = 12)
 options(repr.plot.width=20, repr.plot.height=20)

but it is no help.

Thanks in advance.