It appears that the print styles on English Wikipedia (as far as I have tested) are producing smaller font sizes than other wikis (German and MediaWiki.org tested) when printed from desktop. If I recall correctly they should be consistent across projects at this point?
"Wiki" article from English Wikipedia
"Wiki" article from German Wikipedia
First reported: https://www.mediawiki.org/wiki/Topic:U5nbeixaqf4cgo8t