[Nexus]

Примерно так:

function Movies() {
    const [items, saveItems] = useState([]);
    const [openItemIndex, saveOpenItemIndex] = useState(null);
    
    return <>
        {items.map((item, index) => (
            <div>
                <img src={item.poster_src} onClick={() => saveOpenItemIndex(index)} />
            </div>
        ))}
        
        <Modal show={Boolean(openItemIndex)} />
    </>;
}