It shouldn't matter. The phone charges from a low-voltage DC, the kind you get on a USB cable.
The only way this could happen would be for the wall-wart to fail and pass 220VAC onto the charging cable. Not likely, but possible, I suppose.
So, it cannot be the phone's fault. It could be the charger's fault.
No mention of whether it's an Apple charger or some knock-off charger.
An article I read elsewhere says the woman's family claims it was an Apple charger. But, apparently there are even counterfeit Apple chargers.
The only way this could happen would be for the wall-wart to fail and pass 220VAC onto the charging cable. Not likely, but possible, I suppose.
The UL test for a fuse used to be to put it in a fuse box packed it with cotton wool, with all circuits loaded to rated capacity, then fault the supply to 2500 Volts, simulating a tranmission line falling onto the distribution line entering the house. If the cotton wool caught fire, the fuse failed. Lightning strikes are another possible hazard.
Whatever the wall socket nominal voltage, a lot of bad things can happen on the other side of socket. Levels of protection and likelihood of a fault vary around the globe. In the absence of other information, I would put China in the low level of protect, high level of incidence brackets.
And 220 V is just a whole lot more dangerous than 120. If the transformer failed, faulting the primary to the secondary (it happens) and the person holding the phone was exposed to 220 V (and was reasonably well grounded) the chance of death is pretty high. I have no idea how well the case of the iPhone is insulated from the charging circuit.
“No mention of whether it’s an Apple charger or some knock-off charger. “
Is there a difference in China?