Simulate React-Native fontScale change

example.js

import { Slider, NativeModules } from 'react-native';

<Slider
  maximumValue={ 2 }
  minimumValue={ 1 }
  onValueChange={ (value) => {
    NativeModules.AccessibilityManager.setAccessibilityContentSizeMultipliers({
      extraSmall: value,
      small: value,
      medium: value,
      large: value,
    });
  } }
  step={ 1.5 } />