Hello,
Yes, you can use sections too. But if you prefer using the addBreak method, the code you are using:
$docx->addBreak('page');
is not correct. This is the correct line to add a new page break:
$docx->addBreak(array('type' => 'page'));
You can check it on the API page (https://www.phpdocx.com/api-documentation/word-content/insert-line-column-page-break-Word-document-with-PHP).
Regards.