Carplay Acura RDX Google Maps Volume

I have finally figured out that I need to use the Acura volume control knob to set the volume WHILE Google Maps is speaking. Now the volume seems to work fine except for the last message spoken by Google Maps announcing that I have arrived at my destination. The volume on this last message is insanely higher than the turn by turn volume during the trip. I'm using an iPhone8+ with IOS 12.1 with my new 2019 Acura RDX AWD Advance. This is a small but extremely annoying problem. My wife has the exact same phone and experiences the same problem when using her phone with CarPlay and Google Maps. Any suggestions?