jQuery Siblings

<!DOCTYPE html>
<html>
<head>
    <script src="https://code.jquery.com/jquery-3.7.1.min.js"></script>
</head>
<body style="font-family: sans-serif; padding: 20px;">
    <ul>
        <li>Item 1</li>
        <li id="itemAktif" style="color:blue;">Item 2 (Aktif)</li>
        <li>Item 3</li>
    </ul>
    <button id="btnNext">Sorot Saudara Berikutnya (next)</button>

    <script>
        $('#btnNext').click(function() {
            $('#itemAktif').next().css('font-weight', 'bold');
        });
    </script>
</body>
</html>