Hello,
Yes, setting the format option in createListStyle you can set a custom symbol. For example:
$docx->createListStyle('mystyle', [
0 => [
'type' => 'bullet',
'format' => '-',
],
]);
// list items
$myList = array('item 1', 'item 2', 'item 3');
// insert the custom list into the Word document
$docx->addList($myList, 'mystyle');
Regards.