How to change font size when using PhpWord TemplateProcessor?

Is it possible to change font size when using TemplateProcessor?

I was try to do this, but not working.

$template = new PhpOffice\PhpWord\TemplateProcessor('template.docx');
$template->setValues([
  'name' => 'Nur Muhammad',
  'country' => 'Indonesia'
]);
$template->saveAs('result1.docx');

// Try to change the font size
$phpword = PhpOffice\PhpWord\IOFactory::load('result1.docx');
$phpword->setDefaultFontSize(9);
$phpword->save('result2.docx');

The problem I get:

1. The document styles is lose
2. The font size doesn't change

Thanks in advance.