The code bellow display how to execute the migration not through the command line, but through the code

First we need to load Migration. You can create it from a plugin, in this case the migration file is stored in migrations folder

use Drupal\migrate\MigrateMessage;
use Drupal\migrate_plus\Entity\Migration;
use Drupal\migrate_tools\MigrateExecutable;


// Load migration plugin.
$migration = \Drupal::service('plugin.manager.migration')->createInstance($migration_id);

or load it it from config entity

// Load migration from config entity.

$migration = \Drupal\migrate_plus\Entity\Migration::load($migration_id);

And then run the import

$executable = new MigrateExecutable($migration, new MigrateMessage());
$executable->import().