Can iPhone back up to iTunes over Wi-Fi automatically? I know that my iPhone 8 can back itself up to iTunes over Wi-Fi. It has successfully done so whenever I've manually hit the button in iTunes to back it up immediately.
In iTunes the iPhone is set to &quot;back up to this computer automatically&quot;. It is not clear to me when this automatically happens in the case where I mainly connect the iPhone to iTunes via Wi-Fi. I don't think I've ever had a backup happen automatically -- not over Wi-Fi nor when connecting over USB.
What I can't figure out by searching is whether a Wi-Fi backup to iTunes  can be done automatically. Is it even supposed to be able to do this?
These are additional questions that have come up that might help you understand where I'm standing:

Does an automatic synchronization imply a backup?
If so, does Synchronize automatically when this iPhone is connected apply to iPhones connected to iTunes over Wi-Fi?
Is it possible to back up automatically over Wi-Fi at all?
If so, will it only happen if Wi-Fi sync is enabled?
If it's possible, then how regularly is this done? In other words, at what point can I tell for sure that something is wrong if no backup has been done?

I'm not necessary trying to find answers to all of these questions. They're just different facets of what I'm asking.

Details

macOS 10.14

iOS 13

Devices are not prevented from synchronizing automatically in iTunes
settings.
After consulting with Apple it turns out that 


Automatic sync should happen every time the phone plugs into the computer while iTunes is running
None of my the iTunes installations did this on macOS or Windows, which is an error
To work around this required manually syncing a folder with a photo in it to the phone, on both windows and macOS separately. After that automatic sync starts working. 


From inspection I can conclude that:


Yes
Yes, when plugged into charger
Yes
Haven’t tried yet. Probably, since backup seems to be included as a step in the syncing process. 
Backup should happen within a few seconds of plugging in the charger, five hours from the last backup the same day. Should probably happen every time, regardless of interval.