I found this [1] which says:
"Generally, when the game is in the foreground, persistent threads such as the game thread and render thread should run on the high-performance large cores, whereas other process and worker threads may be scheduled on smaller cores."
There's also a Wikipedia article [2] which talks a little about scheduling. I imagine Android probably has more specific context it can use as hints to its scheduler about where a thread should be run.
[1] https://developer.android.com/agi/sys-trace/threads-scheduli...