The content you're creating is fully responsive and should look great on all devices, new and old. However, while some busy scenes might look good on new generation retina screens, the content could look poor on older devices - such as the iPhone 5.
See the example below: iPhone X vs. iPhone 5 experience.
To preview your content on popular devices - click the Device Preview button at the top-right side of the screen:
You can also enable the Simulate browser UI toggle to factor in the size of the browser components.
Break down your content over multiple scenes.
Long paragraphs are a common turn-off to readers when consuming tappable content.
use larger, bolder fonts, whenever possible
Here's a new take on the scene above: