My A7s II will arrive on Monday. A reviewer online said that the focus tracking only works with a Sony brand lens. Is this accurate?

The widest prime, E-mount, full-frame, Sony brand lens is 28mm. I don't want a lens that I have to shoot in cropped mode. Ideally 20mm. I want focus tracking. Do I have any options?

Tracking isn't great on the A7sII as it lacks PADF like the A7rII, its really hit and miss. Your best bet with any of the AF options is a native E-mount lens. The 28 has the UWA convertor which gives you a 21/2.8. The Batis 25 is the widest AF prime without a convertor. If you need to go wider on FF, the 16-35/4 is your only other option.