Fullscreen

OGPlayerView(
    player = player,
    fullscreenHandler = ActivityFullscreenHandler(activity, lockLandscape = true),
    startInFullscreen = true,          // open directly in fullscreen
    autoFullscreenOnRotate = true,     // rotating the device enters/exits
    onFullscreenExitRequest = { navController.popBackStack() }, // host decides
)

OGPlayerView(
    player: player,
    isFullscreen: $isFullscreen,       // two-way binding
    startInFullscreen: true,
    autoFullscreenOnRotate: true,
    onFullscreenExitRequest: { dismiss() }
)

// Browsers require a user gesture — call from your start button:
startButton.addEventListener("click", async () => {
  await el.enterFullscreen();
  player.load({ url, title: "My movie" });
});

// Host-intercepted exit (the in-player button):
el.config = {
  onFullscreenExitRequest: () => {
    el.exitFullscreen();
    location.href = "/library";
  },
};

Notes per platform:

Android / iOS — startInFullscreen opens the screen already expanded; autoFullscreenOnRotate follows the physical sensor.
Web — there is no startInFullscreen flag because browsers only allow fullscreen from a user gesture; the “starts in fullscreen” flow is your start button calling enterFullscreen(). The Esc key always exits directly (platform behavior that cannot be intercepted); onFullscreenExitRequest covers the in-player button.
The fullscreen chrome steps up automatically (bigger targets, bigger type) on every platform.