Hello Rb50,
Thank you for using Apple Support Communities. Based on your post, you'd like to disable the Driving Focus on your iPhone.
First, be sure this is a feature you want to disable. Removing the Driving Focus will allow you to receive notifications while moving in a vehicle.
With that said, you can open Settings > tap on Focus > Driving > scroll down to Turn on Automatically and change it to 'Manually' or 'When Connected to Car Bluetooth' instead of 'Automatically'. You can also delete the Driving Focus in Settings > Focus > Driving > Delete Focus.
Resources:
Stay focused while driving with iPhone
Use Focus on your iPhone, iPad, or iPod touch
Hoping this helps out, take care.