The fastest way for testing Dynamic Type while developing, and to quickly see how your app's UI flows, is by using the "option + cmd + plus/minus" to increase/decrease the text size in your simulator.
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It is possible to use custom fonts and for them to still work great with Dynamic Type. You need to define the default size and use UIFontMetrics to get the scaled font for each one of the styles you'd like to use. https://developer.apple.com/documentation/uikit/uifontmetrics/scaledfont(for:)
The Accessibility Inspector let’s you run an audit of the current screen in your simulator or device. It can find some basic issues like color contrast issues, touch target sizes that are too small, etc. It can also provide with fix suggestions.
Make sure you support Dynamic Type up to the largest text size available. Take into account that there are five extra accessibility sizes available from the Accessibility Settings. It can make a huge difference for lots of users.
