When I plot several plots in an .Rmd file with flexdashboard, the second plot shows up much smaller than the first. Here is a screenshot from the reprex below.

Why the second plot is much smaller than the first and how can I make them the same size?

I understand flexdashboard often resizes items to fit screen, but am lost on what exactly is happening here. I found the exact same question on SO from Oct 2021: