Flex

const styles = StyleSheet.create({
    container: {
        flex: 1,
        flexDirection: "column"
    },
    box: {
        flex: 1
    },
    box1: {
        flex: 1,
        backgroundColor: "#2196F3"
    },
    box2: {
        flex: 10,
        backgroundColor: "#8BC34A"
    },
    box3: {
        flex: 0.5,
        backgroundColor: "#e3aa1a"
    }
});