Index adds persistent manual hierarchy ordering to Unreal Engine's standard World Outliner. Change the order of your actors and folders, changes will persist through level saves.

Documentation & Instructions: https://github.com/mippi-the-dork/Index/blob/main/README.md

This plugin is available on FAB for convenience and to support the plugin creator.
This plugin is free on github: https://github.com/mippi-the-dork/Index