Looking like we are getting another X-series phone from Vivo as recently, a listing on Geekbench as appeared with the name Vivo X21UD A. The UD stands for Under Display which indicates that this phone will come with the fingerprint sensor placed under the screen.
According to the listing, the X21 will come with a Snapdragon 660 chip, and 6GB of RAM. It has managed to score 1608 on the single-core test and 5852 on the multi-core test which is very decent for a phone running a mid-range processor. Similar to the X20, the X21 should also come with a bezeless display. The listing also tells us that it will ship with Android 8.1 out of the box but other than that, there is no other information about the phone, other than the processor and RAM.