: Hover your mouse over the video player and click the Miniplayer icon (a small square within a larger square) located in the bottom right corner, typically between the settings and theater mode icons.
: Press the I key on your keyboard to instantly toggle the Miniplayer on or off. MSDMiniplayer
: If it isn't working, check your device settings under Apps > Special app access > Picture-in-picture (Android) or Settings > General > Picture in Picture (iOS) to ensure the feature is enabled. How To Turn On Miniplayer On YouTube - Step By Step : Hover your mouse over the video player