There are many ways to configure the Dynamic Type on your device or in the iOS Simulator
When setting up a new iOS device, there's a full screen prompt for setting the global Dynamic Type setting. This leads to Dynamic Type being the most used accessibility setting.
In Settings > Control Center, you can add the "Text Size" control, allowing you to change Dynamic Type on the fly. Using this control, you can adjust the global setting as well as the current app's specific setting on iOS 15+. (Available in the simulator?)
In Xcode, you can use the preference settings pane to adjust the Dynamic Type setting of the app you're currently debugging.
%% And finally, in Xcode previews, you can adjust Dynamic type using a modifier. Here's an example that will easily allow you to test for many different sizes. %%