Hi hi, it's like this: https://x.com/sanghendrix96/status/1827893671754387925/video/1
Pay attention to the dog and the guy in black. You can set up the AI of your party members however you want.
My setup was:
For the dog: Automatically chase enemy and attack them then retreat to player
For the guy in black: Stay by your side and just cast a spell from time to time
So basically yes, they can move on their own and do whatever you set them up to do. :D