Hello, amiel147. Thank you for posting your question to the Apple Support Communities. We understand that you are looking for the best way to manage the audio output of your device when you are getting directions from the Maps app. We would be happy to go over the available options with you.
To get started on this, we would like to provide you with a helpful Apple Support article. This article explains how you can access and customize the Control Center on your device:
Access Control Center on your iPhone and iPod touch - Apple Support
With the Control Center open, you should be able to choose the audio output for your device towards the top right.
You may also find this second article help. This article explains which features you can access when Maps is following a route:
Things you can do while following a route in Maps on iPhone - Apple Support
We hope that this information allows you to set up and use Maps as you would like. Please let us know if you have any other questions about these features.
Have a great day!