Yes, Vivo X21 does have integrated App Clone feature.
Yes, Vivo X21 does have the portrait mode in the front camera. In fact, both the cameras - front as well rear - supports the portrait mode.
Yes, Vivo X21 does have the Smart Split function.
Yes, Vivo X21 does have the eye protection mode.
Vivo X21 is an all-rounder with good performance, decent camera performance and a snazzy new in-display fingerprint scanning technology at the heart of the device.
For the most part, the X21 is a worthy mid-tier device.