I wish the adjustsFontForContentSizeCategory was true by default. Instead, you need to configure it that way so elements adjust their font size as the content size category (dynamic type) changes when a preferred font is used for a given style.

Screen with the Cineaste app open. Then, the Text Size menu in Control Centre is opened and the largest font size is selected. If the .adjustFontForContentSizeCateogry property is true for the labels in the app, the app will react and increase the font size immediately without needing to close and open the app again, or pop and push the presented screen. But if it is false, the app would not change at a first glance. You'd have to pop and push the screen or close and open the app again for the new text size to take effect.