It doesn't look like the OnePlus 6T will come with a triple camera
https://www.techradar.com/news/it-doesnt-look-like-the-oneplus-6t-will-come-with-a-triple-camera
We already know that the OnePlus 6T is set to drop the headphone jack and include an in-display fingerprint scanner, but until now we are yet to learn much about the rear camera.
Some expected OnePlus to upgrade to a triple camera on the rear of the phone, much like the Huawei P20 Pro and even the just announced Samsung Galaxy A7 (2018), but two new pieces of information suggest it won't sport that tech.