first.php

<?php

function createAccountFor($type, $name = null, $model) {
  $parameters = [
    'name' => $name,
    'model_id' => $model->id,
  ];
  
  return factory(Account::class, $type)->create($parameters);
}

// Usage

$jaggy   = $this->createClient('Jaggy');
$typekit = $this->createAccountFor('client', 'Typekit', $jaggy);

refactored.php

<?php

function createAccountFor($model, $name = null, ) {
  $parameters = [
    'name' => $name,
    'model_id' => $model->id,
  ];
  
  $type = strtolower(str_replace("App\\", '', get_class($model)));
  
  return factory(Account::class, $type)->create($parameters);
}

// Usage

$jaggy   = $this->createClient('Jaggy');
$typekit = $this->createAccountFor($jaggy, 'Typekit');