I've been hoping for a while now that digital assistants like Alexa and Google Assistant would implement that feature and respond in a volume similar to the one you asked your question in. That way you wouldn't have to be constantly messing with the volume to make sure you can hear the assistant without it being too loud.
On the other hand, if you're further from the device, it will hear you less loudly, while it should respond more loudly. Maybe it could distinguish speaking softly from speaking far away somehow.
I'm not sure this is a bad idea...