Create a New Content Entity During Module Update

module_name.install

<?php

use Drupal\Core\Database\Database;

/**
 * Create the entity table if it does not exist.
 */
function twist_opsf_update_9001(){
  //check if the table exists first. If not, then create the entity.
  if(!Database::getConnection()->schema()->tableExists('maestro_process_status')) {
    \Drupal::entityTypeManager()->clearCachedDefinitions();
    \Drupal::entityDefinitionUpdateManager()
      ->installEntityType(\Drupal::entityTypeManager()->getDefinition('maestro_process_status'));
  } else {
    return 'Process Status entity already exists';
  }
}