Audio volume
Use wpctl (PipeWire). Do not open a settings GUI for this.
Set volume
wpctl set-volume @DEFAULT_AUDIO_SINK@ 40% # absolute
wpctl set-volume @DEFAULT_AUDIO_SINK@ 5%+ # relative
Tier: reversible. Undo: set the previous value, read first with wpctl get-volume @DEFAULT_AUDIO_SINK@.
Mute / unmute
wpctl set-mute @DEFAULT_AUDIO_SINK@ toggle
Tier: reversible.
Switch output device
wpctl status # find the sink id under "Sinks"
wpctl set-default <id>
Tier: reversible. Undo: set-default back to the previous id.
Verify
wpctl get-volume @DEFAULT_AUDIO_SINK@ prints the current volume and mute state.