onlyone-8.x-1.x-dev/onlyone.install

<?php

/**
 * @file
 * Install, update and uninstall functions.
 */

/**
 * Set the default value for the new variable onlyone_redirect.
 *
 * @see https://www.drupal.org/project/onlyone/issues/3104005
 */
function onlyone_update_8001() {
  \Drupal::service('config.factory')->getEditable('onlyone.settings')->set('onlyone_redirect', TRUE)->save();
}