Programmatically create a menu link in Drupal 8

create_menu_link.php

<?php

use Drupal\menu_link_content\Entity\MenuLinkContent;

MenuLinkContent::create([
  'title' => 'Hello World',
  'link' => ['uri' => 'internal:/node'],
  'menu_name' => 'main',
  'weight' => 10,
])->save();

Where that code should be placed so it's executed only once? Also, what about translatable menu items? How to add menu item that has different title and url (path) for different languages?