Trigger cron internally using PHP
a way to do that :

create customcron.php in the drupal root with the content :

&lt;?php

use Drupal\Core\DrupalKernel;
use Symfony\Component\HttpFoundation\Request;

$autoloader = require_once 'autoload.php';

$kernel = new DrupalKernel('prod', $autoloader);

$request = Request::createFromGlobals();
$response = $kernel-&gt;handle($request);

// Load cron service and run cron.
\Drupal::service('cron')-&gt;run();

$kernel-&gt;terminate($request, $response);


then run :

php customcron.php


i would not let the file customcron.php in the root because anybody could then execute it from the browser.

A simple way to avoid that is moving the file customcron.php to drupal root only for the time you execute it or maybe have an unguessable file name instead of customcron.php