How to use picture in picture in Zenfone 6
If you are referring to the picture-in-picture in ZenFone's PhotoCollage, PhotoCollage has stopped built-in. If you need it, you can go to PlayStore or APKmirror to find it or install other apps with similar functions.
He probably means PiP android feature that allows content to be displayed on top of the other app. It's handled by app developer, not phone. Some of apps using Picture in Picture can activate it when minimized, like Google Maps and Youtube.
Yes.How it's works in Zenfone 6???
It's not standardised. You have to check settings in Maps or YT. Activate option related to PiP mode. Then, when you press home button it will show in a small popup window instead of minimizing. Not every app supports it.
PiP with YouTube is a premium feature. You have to pay for a subscription to get it
You can run a Youtube link (or probably any media link) as a "stream" in the media player app VLC, which works fine in PiP mode.