Your app supports Dynamic Type (the setting that tells apps to adjust the text size).

To increase or decease text size on your iPhone Settings:

1. Open the native Settings App
2. Tap on "Display & Brightness"
3. Towards the bottom, find "Text Size"

Also to add the Text Size tool to the control center, so you can swipe up (older iPhone) or swipe down from the right side of the notch.

1. Open the native Settings App
2. Tap on "Control Center"
3. Select "Customize"
4. Tap on the "+" next to "Text Size"