change single.php when using advanced layout builder

Hello, I’m using some code to use advcaned layout builder in posts but now I want to make some change to the template. Which files should I change in the child theme? This is the code I’m using for using advanced layout builder:
add_filter(‘avf_builder_boxes’, ‘add_builder_to_posttype’);

function add_builder_to_posttype($metabox)
{
foreach($metabox as &$meta)
{
if($meta[‘id’] == ‘avia_builder’ || $meta[‘id’] == ‘layout’)
{
$meta[‘page’][] = ‘post’; /*instead add the name of the custom post type here*/
}
}

return $metabox;
}