Is body font size too big?

I set the base font on this website to 19px. 

Clients are requesting 16px because belive font may be too big. I want to strongly advise against this, but want to double check with more experienced designers. Is the base font too big? My impression was that for text heavy sites, I should lean towards bigger font size. And for interaction heavy sites, lean towards smaller. Here's an example of a typical page on the site:

https://www.civilrightsteaching.org/resource/big-shoes-fill

I think 19px is a bit big

Default size in browser is 16px