Enable Features

• In TYPO3 V11 or V12 : Admin Tools > Settings module > Configure extension > rt_pages_tree_icons.

Enable changing pages tree icons when editing page properties in behavior tab > Use as Container.

Enable features

Page Module > Edit Page properties > Behavior > Use as container

PHP - Enable Features

Enable changing pages tree icons when editing page properties:

 <?php
 // TYPO3 V11: typo3conf/LocalConfiguration.php
 // TYPO3 V12: config/system/settings.php

 return [
    'EXTENSIONS' => [
       'rt_pages_tree_icons' => [
         'diplayIconsInBehaviourTab' => '1',
      ],
   ],
];