In Android 10, the picture-in-picture (PiP) mode for videos only allows users to move the window, pause/kill playback, revert back to full-screen mode, and open the PiP settings. There isn’t a way you can do anything else like resize the window. It appears that Google is testing just that and might release it with Android 11.
XDA-Developers Editor-in-Chief, Mishaal Rahman, has spotted the ability to resize a picture-in-picture window in the third developer beta of Android 11 that was released earlier today. Users can simply touch any corner and drag inward or outward to shrink or expand the window.
Thankfully, shrinking or enlarging the PiP window will keep the aspect ratio intact so that the video you are playing doesn’t look distorted. But do keep in mind that this is a developer preview we are talking about, so there is no assurance that this feature will arrive with the stable Android 11 update.