set border bottom width react code example

Example: border bottom react native

It seems borderBottom doesn't work for the Text component. You can either add a View wrapper and supply borderBottom to it or add a TextInput and make editable={false}

<View style={styles.headerWrapper}>
    <Text style={styles.header}> Registration </Text>
 </View>
...

headerWrapper: {
    borderBottomColor: 'red',
    borderBottomWidth: 2,
    marginBottom: 30,
},
header: {
    fontSize: 36,
    alignSelf: 'auto',
    color: 'red',

},