Programatically Modifying Config - Font Size

     $settings['editor']['formats'][$text_format_id]['editorSettings']['config']['fontSize']['options'] = array(
        array(
          'title' => '90%',
          'model' => 'fontsizeNinety',
          'view' => array(
            'name' => 'span',
            'styles' => array(
              'font-size' => '90%',
            ),
            'priority' => 7
          ),
        ),
        'default',
        array(
          'title' => '110%',
          'model' => 'fontsizeOneTen',
          'view' => array(
            'name' => 'span',
            'styles' => array(
              'font-size' => '110%',
            ),
            'priority' => 7
          ),
        ),
      );