Search for any post ID

No. Relevanssi does understand the WP_Query p parameter to restrict the search by post ID.

However, if you want to search by post ID, it’s very simple to make that happen:

add_filter('relevanssi_content_to_index', 'rlv_index_post_id', 10, 2);
function rlv_index_post_id($content, $post) {
    $content .= " " . $post->ID;
    return $content;
}

Add that to theme functions.php, reindex and searching for post ID’s works.

Wow, thanks for the quick reply and amazingly positive answer. Much appreciated. ??

Helped me a lot.. thanks