Google says you can with these steps. Let us know if this works.
To stop your Samsung music player from automatically playing in your car, go to Settings within the Samsung Music app and turn off the Allow external devices to start playback option. Additionally, if you use Android Auto, you can disable auto-play in its settings by going to your phone's main settings, selecting Connected devices > Android Auto, and turning off "Start music automatically".
For Samsung Music app
This video demonstrates how to disable automatic music playback in the Samsung Music app: