Enlargement of size of the device font will sometimes break (Styling wise).
For React native 0.58+
Preferable to keep font scaling but you can limit it by using Text new prop maxFontSizeMultiplier
For React native 0.56+ use Levi's answer
Text.defaultProps = Text.defaultProps || {};
Text.defaultProps.allowFontScaling = false;
For React native 0.55 and lower
Add Text.defaultProps.allowFontScaling=false at the beginning of the app (e.g. main.js or app.js etc ...) to apply this prop on all Text components through out the whole app.