Source of these is a Chinese website Macotakara:

– iPhone 12 4G is to be released in late October, and the 5G variant in November,
– it is also possible that both will come out in September,
– according to some people, there will be no iPhone 12 4G variant,
– the phone will be released in four versions, normal, Pro and two more,
– iPhone 12 Pro will have a rather silly 2775 mAh battery,
– the normal iPhone 12 will have an even sillier 2227 mAh.