I’m struggling to size fonts between Retina devices. For instance, on a MacBook Pro, the fonts look fine. But on a standard 2017 Macbook (which is also Retina) they do not scale. I tried targeting the font sizes via custom code and even tried using Rem, Em and percentage scaling but it doesn’t seem to work.
You can scale your font using view width seen as “vw”.
There is a really good post at CSS Tricks about Fluid Typography. It uses vw and a font style calculation which you are able to put into a style tag within the head of your page via page settings > custom code.
Not too sure if I am allowed to link to a 3rd party site but if you are interested to find it you can google it or PM for a link.