Follow focus on cinema camera?
On professio al sets with a camera crew, there is an extra person which pulls the focus.
We don't really use automatic focus.
This needs some training, but it's not so hard to pull off.

Normally, you attach 15mm rods to the camera body, on which you then mount the FF system, "wired" systems start at around 20$, useable ones at around 100$.

Wireless you could take a Tilta Nucleus Nano for 230$