You can clone the expo-example-app from this repo.
After cloning, run npm install, then npm start and scan the presented QR code in the Expo app on your preferred device.
The app has an on/off switch for using react-native-size-matters, so you can test yourself how the app will look with and without scaling.
It is expected to look good on every device you want - iOS or Android, phone or tablet, basically anything (please let me know if isn't).
There are also some attached screenshots in the repo if you don't feel like cloning.