Allow installation from "Unknown Sources" in your phone settings.
The Oppo A16 comes with ColorOS and a stock camera app that does a decent job in broad daylight. However, the limitations become apparent in specific scenarios. Here is why installing the GCam Port is a game-changer for A16 users: oppo a16 gcam port
: Better edge detection and more natural-looking background blur (bokeh). Allow installation from "Unknown Sources" in your phone