ACF Relationship – Limit to specific pages

Found a solution that works:

add_filter('acf/fields/relationship/query/name=products', 'exclude_id', 10, 3);

function exclude_id ( $args, $field, $post ) {

    $args['post__not_in'] = array( $post, 9, 10, 11 );

    return $args;
}

Added in functions. This will exclude the pages with id 9, 10 and 11.