I know this has been asked in the past and it appears that the post are locked.
I am requesting the ability for Plex to be able to keep plying on a locked screen. The previous reason for this not being added was it was a limitation of android.
Currently The Firefox as well as other streaming app can preform this without flaw, so id assume this capability is now possible.
There’s a rather old feature suggestion asking for that option.
I suggest you comment/vote in that thread in order to avoid distracting votes (despite the age of the other thread).