The same source now shared some more info regarding that. He clarified exact launch dates for the US, Europe, and India. It seems like the OnePlus 7T series will become available for purchase on October 15, and will launch even sooner than that.
The phone's initial launch will take place on September 26, in India. That is quite interesting, as India will apparently become a launch country for the OnePlus 7T series. That is somewhat odd, but there you go, presumably that the info is correct.
The US and European launches will take place a bit later, in October. According to the provided info, the phone will launch on October 10 in both the US and EU. It is not known whether OnePlus will host separate events for those launches, but it probably will.
Little is known about the OnePlus 7T series, almost nothing, in fact. Other than a couple of fake leaks, and these release dates, we know nothing. The alleged OnePlus 7T Pro surfaced in real-life images, but it turned out that info was not legit. Those images showed the OnePlus 7 Pro prototypes, not the OnePlus 7T Pro ones.
OnePlus is presumed to launch both the OnePlus 7T and 7T Pro, but we'll have to wait and see what will happen. If these dates end up being accurate, this will be the earlier launch of a OnePlus T-series device ever. At first, those devices arrived in November, then October, and it seems like the initial date has been moved to September this time around.
At this point, we can only guess what will the OnePlus 7T and 7T Pro bring to the table. Both phones will probably be made out of metal and glass, and won't make major design changes. It's probable that both will resemble the OnePlus 7 Pro, which means that the notch may disappear completely. That's at least our guess, as it would be weird for OnePlus to bring the OnePlus 6T design to another phone.
Qualcomm's Snapdragon 855 Plus processor will almost certainly fuel both T series smartphones. That is the latest and greatest processor Qualcomm has to offer, and an upgrade over the Snapdragon 855… but not a large one.
The OnePlus 7T's base model will probably include 6GB of RAM, while the OnePlus 7T Pro's will include 8GB of RAM. At least as far as the OnePlus 7 series is any indication. Price tags will probably be similar to the ones for the OnePlus 7 smartphones.
The sizes of these two phones are expected to be similar to their OnePlus 7 counterparts. The OnePlus 7T will probably include a fullHD+ display, while the OnePlus 7T Pro will ship with a QHD+ one.
Some rumors suggested that OnePlus may include an under-display camera in these two smartphones, or at least the Pro model. While that is possible, it's not that probable. Xiaomi and Vivo have already shown their prototypes with under-display cameras, and Vivo is OnePlus' sister company. Having said that, one of those two companies will probably release a phone with an under-display camera first, so the OnePlus 8 or 8T is more likely to sport such tech.