Вы можете достичь этого, используя обработчик завершенных форм wp.
function wpform_set_submitted_cookie( $fields, $entry, $form_data, $entry_id ) {
// Set the third parameter to specify a cookie expiration time,
// otherwise it will last until the end of the current session.
setcookie( 'wpform_form_submitted', 'true' );
}
add_action('wpforms_process_complete_{form-ID}',
'wpform_set_submitted_cookie',10,4);
function wpform_protect_confirmation_page() {
if(is_page('{your-page-slug}')&&isset( $_COOKIE['wpform_form_submitted'])) {
wp_redirect( home_url( '/' ) );
exit();
}
}
add_action( 'template_redirect', 'wpform_protect_confirmation_page' );