$html = '<ul><li>Html</li><li>to</li><li>indent</li></ul>';
$beautify = new Beautify_Html(array(
  'indent_inner_html' => false,
  'indent_char' => " ",
  'indent_size' => 2,
  'wrap_line_length' => 32786,
  'unformatted' => ['code', 'pre'],
  'preserve_newlines' => false,
  'max_preserve_newlines' => 32786,
  'indent_scripts'	=> 'normal' // keep|separate|normal
));

echo $beautify->beautify($html);