The next few images are from my Sony A7III.
I made the mistake of trying an A7III back when I had my A7RII.
The autofocus is light years better in the MKIII.
As you have likely noticed, I take a lot of photos of our dogs.
And the mkIII is just far better at it.
The only issue with the A7mkIII is the IBIS is not very impressive.
I didn't expect it to be the champion that Olympus was, but I would hardly call it even decent.
I took a few photos at 1/40 of a second on this page and you can see much of them have motion blur.
And this with a 28mm lens!
And the IBIS is literally worthless for video.
I use my Pixel Phone instead. It's a bit frustrating because I was hoping to get some decent video with this mkIII.
Basically - no panning. It's nearly more stable if you turn the IBIS off.

But yeah - the AF is absolutely amazing. And animal eye AF is just amazing.
It doesn't have tracking per se, but it basically tracks what you want it to unless there are loads of other subjects milling about.