Form Text Size

You can play with the Image On Load technique and other variations to do this automatically in certain places. Play with this next thing too because it needs it, I had to adjust the sheet index(window.document.styleSheets[3]) to insert it into an empty sheet(I tried on stack overflow first) because you cannot insert CSS into a stylesheet that is called from an outside URL like they had. The way I did that was to just type "window.document.styleSheets" and see which sheets were returned and pick one that was "local" rather than from a cdn. This command will make everything in the body larger but you can adjust that to change whatever you want.

var sheet = window.document.styleSheets[3];
sheet.insertRule('body { font-size: 3em; }', sheet.cssRules.length);

There might be other ways and I'm not going to guarantee this will even work for your use case, but it is worth a shot.