Install a new custom entity in Drupal 10 existing module

my_module.install

<?php

/**
 * Scenario: We just added a new content entity via drush generate entity:content. We want to install it.
 * The module was already enabled, so we can easily install it with 2 lines.
 */
function superentity_demo_update_8001()
{
    $entity_type_manager = \Drupal::entityTypeManager();
    \Drupal::entityDefinitionUpdateManager()->installEntityType($entity_type_manager->getDefinition('id_of_my_entity'));
}