Low In-Call voice handset volume problem on G6 Plus (evert)

Voice volume too low on Motorola g6 plus-Evert when in speaker mode.
What I’m looking for is a way to increase output volume on speaker during a voice call.

I’ve found a way to pull the mixer_paths.xml file, and after editing push this file back to the phone.
adb pull /system/vendor/etc/mixer_paths.xml
Then edit the file.
adb shell su -c "mount -o rw,remount /vendor;"
adb push mixer_paths.xml /system/vendor/etc/mixer_paths.xml
…mixer_paths.xml: 1 file pushed. 0.3 MB/s (36935 bytes in 0.112s)

Since there are many values in the mixer_paths.xml file, I would like to ask help which settings pertain to the voice-speaker volume.

A big THANKS in advance,