Dynamic Type is a feature that lets a user change the font size (smaller or larger) of the whole system or a particular app. To support it, choose a preferred font based on one of the 11 supported text styles: Large title, heading, body...

Four apps showcasing the available text styles: Large title, title 1, title 2, title 3, headline, subhead, body, callout, caption 1, caption 2 and footnote. Each one of the four apps has a different dynamic type option selected: extra small, large (which is the default), extra extra extra large and accessibility extra extra extra large. So it is easy to compare how these styles change for different dynamic type options. To support it, you can configure a preferredFont for a label, passing a textStyle.