https://www.lighterra.com/papers/videoencodingh264/
Although discussing x264 mainly, the above link does cover b frames, ref frames and much more.
I’m no expert but as I understand it low latency is more used/required for streaming.
The defaults in Magix are probably ok. Vbr HQ is what I choose in Nvenc.
2 ref frames and maybe 3/4 b frames in x264, it all depends of course on so many things, sometimes conflicting, do you want high quality, low file size etc, choosing one can conflict with another. Google it.
Steve was pointing to that usage of x264 within Magix because if you install it then you get to play with so many many different settings.