script.php

$jsonItems = [
    '@context' => 'http://schema.org',
    '@type' => 'BreadcrumbList',
    'itemListElement' => []
];
$jsonItems['itemListElement'][] = [
        '@type' => 'ListItem',
        'position' => $index + 1,
        'item' => [
            '@id' => $link,
            'name' => strip_tags(html_entity_decode($title))
        ]
    ];
    
    
    echo '<script type="application/ld+json">
                '.json_encode($jsonItems, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES).'
                </script>';