On iOS devices within accessibility section of general settings you can change the text size, making it (much) larger or smaller. I hadn’t come across this before, but to get your application to work with the user’s settings you use ‘Dynamic Type’. These are “UIFontTextStyle” elements which will automatically size around the user’s text size setting. The settings available and their relative sizes are: Large Title – 44pt Title 1 – 38pt Title 2 – . . .
Just a note about TypeScript Playground, an online REPL for TypeScript. Been around a while, but really useful for trying out a quick bit of TypeScript.