Styles are applied in React Native using StyleSheet

import React from 'react';
import {StyleSheet, Text, View} from 'react-native';
const App = () => (
  <View style={styles.container}>
    <Text style={styles.title}>React Native</Text>
  </View>
);
const styles = StyleSheet.create({
  container: {
    flex: 1,
    padding: 24,
  },
  title: {
    marginTop: 16,
    paddingVertical: 8,
  },
});
export default App;

Platform

In StyleSheet’s props, you can use this to write styles individually for android and ios

import {Platform, StyleSheet} from 'react-native';

const styles = StyleSheet.create({
  height: Platform.OS === 'ios' ? 200 : 100,
});

Also We can use Platform.Select

import {Platform, StyleSheet} from 'react-native';
const styles = StyleSheet.create({
  container: {
    flex: 1,
    ...Platform.select({
      ios: {
        backgroundColor: 'red',
      },
      android: {
        backgroundColor: 'green',
      },
      default: {
        // other platforms, web for example
        backgroundColor: 'blue',
      },
    }),
  },
});