There is a MediaQuery property in Flutter which you can use to restrict scaling of your fonts on different devices based on the device accessibility settings.

main.dart

MediaQuery(
    // This will set scaling for the app to always remain 1:1 globally
  data: MediaQuery.of(context).copyWith(textScaler: TextScaler.linear(1.0)), 
    // Wrap your Material App with MediaQuery to implement this
  child: MaterialApp.router(
    title: 'ScaleFactorText',
    ...
    ),
  );