[WordPress] - It allows you to use CPT and pages relative

cpt_parent_page.php

add_action('parse_request', 'cpt_parent_page' );
function cpt_parent_page( $wp ) {
	if ( isset ( $wp->query_vars['attachment'] ) && ! empty( $wp->query_vars['attachment'] ) ) {
		$page = get_page_by_path(
			$wp->request,
			OBJECT,
			array( 'page', 'book' )
		);
		if ( $page instanceof WP_Post ) {
			$wp->query_vars = [ 'page_id' => $page->ID ];
		}
	}
}