Oppo announced the Find X5 series in February, so the X6 series should be available around the same time next year. The initial rumours about the phones are already circulating on Weibo, with expectations of two generations of Snapdragon 8-series CPUs being used.
Of course, the premium Oppo Find X6 Pro will have the forthcoming Snapdragon 8 Gen 2. It will most likely have a 2K (or QHD+) display and a camera with a 1" sensor. Oppo, Vivo, and Xiaomi are all working on phones with 1" cameras for next year, according to Digital Chat Station (Xiaomi already launched the 12S Ultra this year).
The Snapdragon 8+ Gen 2 is likely to power the standard Oppo Find X6. 1, according to Digital Agent 007. Oppo is rumored to be working on a Snapdragon 8+ Gen 1 version of the Find X5 (the original phone uses the 888), but the fast approaching Find X6 may obsolete it pretty quickly. Anyway, it is said to have a 1.5K display, a newly emerging term for 1,220px horizontal resolution.
The Find X5 Pro is also available with the Dimensity 9000 chipset. MediaTek is almost surely working on a successor processor, thus it's feasible that Oppo may adopt it as well for one of the Find X6 series.
Whatever processors are used in the X6 flagships, they will almost certainly include unique MariSilicon image processing as a distinctive feature for its Hasselblad camera. However, we haven't heard anything about it yet.
