wordpress if thumbnail show else

<?php
    // Step 1: Get the post thumbnail URL
    $thumbnail_url = get_the_post_thumbnail_url();

    // Step 2: Check if the thumbnail exists
    if ($thumbnail_url) {
        // Step 3: If thumbnail exists, display it
        echo '<img src="' . esc_url($thumbnail_url) . '" alt="Post Thumbnail">';
    } else {
        // Step 4: If thumbnail doesn't exist, display a default image or fallback content
        echo '<img src="' . esc_url(get_template_directory_uri() . '/images/default-thumbnail.jpg') . '" alt="Default Thumbnail">';
        // Alternatively, you can display alternative content like a message
        // echo '<p>No thumbnail available</p>';
    }
?>