From headline' style remove height, justifyContent and alignItems. It will center the text vertically. Add textAlign: 'center' and it will center the text horizontally.
headline: { textAlign: 'center', // <-- the magic fontWeight: 'bold', fontSize: 18, marginTop: 0, width: 200, backgroundColor: 'yellow', } headline: { textAlign: 'center', // <-- the magic fontWeight: 'bold', fontSize: 18, marginTop: 0, width: 200, backgroundColor: 'yellow', }