How do I use the picture-in-picture function?

After Android 8.0, Google emphasize the fluency in Multitask processing scene. Picture-in-picture mode brings you a more fluent operation experience. For example, if you are watching a movie on Netflix, you can now shrink that screen into a suspension window, allowing you to also view your Calendar app, look up information or carry out other tasks. It’s different from the split screen function. You only need to press the Home button to launch this function, and then just flip the suspension window down to stop it.