Set random images from library

functions.php

$args = [
    'post_type' => 'post',
    'posts_per_page' => -1
];

$results = new WP_Query($args);

while ($results->have_posts()): $results->the_post();
    $images = [
        793,
        734,
        722,
        367
    ];
    $image = $images[array_rand($images)];

    update_post_meta($post->ID, 'listing_image', $image);
    update_post_meta($post->ID, '_listing_image', 'field_image_32dac18920718ed6498d3c5e31fcdfd3');
endwhile;