The OnePlus 8T will have a 6.55” display – the same size as its non-T predecessor. However, it seems that the phone itself will be larger than before. @OnLeaks posted the dimensions of the device – 162.8 x 75.5 x 8.4 mm, going up to 9.3 mm for the camera hump. Previously, the leakster shared renders of the 8T. We’ve prepared a simple schematic to show the relative sizes of the T-phone and the original 8-series (including the thickness - the 8T is almost as thick as the 8 Pro). Note that this year there will be no T Pro model, instead the 8T is getting multiple upgrades like 120 Hz...
Source: https://www.gsmarena.com/the_oneplus_8t_will_be_taller_wider_than_the_oneplus_8_despite_having_the_same_screen_size-news-45582.php