how to downmix 5.1 audio from a MKV playback into 2.0 ?

[bestofcomputer]

hi.
how to downmix 5.1 audio from a MKV playback into 2.0 ?
i have vlc 3.0.21 for windows 11.
i used makemkv to rip a video from a blu ray (movie in dolby) into a mkv file containing 5.1 audio.
if i play the mkv file with vlc and default settings, will it play all the 5.1 channels, or only the left or right or center channel (mono), or only the left and right channels (2.0) ?
and how can i find it out ?
my pc is connected to my av receiver with 7.1 speakers.
will it play it in dolby or pcm ?
and how to force vlc to downmix all 5.1 channels into stereo 2.0 channels ?
and will it it be in dolby or pcm ?
thanks.

[Lotesdelere]

AFAIK, if your system audio output is stereo then VLC will automatically downmix to stereo.