I have been searching and can not see if this has been asked already. I am trying to see if there is a way to give someone remote admin access to my server to allow them to Update libraries, and edit Meta data / Tags etc.
Administrative tasks are only allowed for the server admin - i.e. you.
Whether you are signed into your plex account from remote or not doesn’t matter, as long as remote access in Plex is generally working.
You cannot give another user administrative permissions.
You’d either have to give him your own plex credentials (not recommended)
or use a workaround, like setting up a file share where the user can upload his content.
The library updates are then either triggered manually by you or you let Plex server update its libraries periodically (don’t set the time between updates too short!)