Canon EOS R System cameras have taken AI autofocus to another level.
The intelligent subject detection in models such as the EOS R6 Mark II and EOS R3 is so good that you really can let the camera take care of autofocusing, while you work on other aspects of creating a great photo.
There are still occasions when you’ll want to touch up the focus distance manually or take complete control though. If there’s not enough contrast between the subject and the rest of the scene, for example, then there won’t be anything for the AF system to ‘bite’ onto. The lens will repeatedly try to focus back and forth, from the closest distance to the horizon and back again, without locking on. The same can happen in low light conditions.