Hi @Schweizerhörer
Apologies for the misunderstanding - perhaps it was me or one of my colleagues who put this thread in the Google Assistant category and not yourself.
In that case, there are no such settings for Sonos Voice Control, but I will convert this thread into a feature request for there to be more control available.
Regardless, we are aware of this issue affecting voice assistant comparative volumes and aim to resolve it soon.
I hope this helps.
"Common sense is the collection of prejudices acquired by age eighteen." - Albert Einstein