SystemUiController有一个getter/setter方法用于系统栏的可见性：

val systemUiController: SystemUiController = rememberSystemUiController()

systemUiController.isStatusBarVisible = false // Status bar
systemUiController.isNavigationBarVisible = false // Navigation bar
systemUiController.isSystemBarsVisible = false // Status & Navigation bars

您可以在MainActivity中执行此操作

override fun onResume() {
    super.onResume()
    window.decorView.systemUiVisibility = View.SYSTEM_UI_FLAG_FULLSCREEN
}

override fun onStart() {
    super.onStart()
    window.decorView.systemUiVisibility = View.SYSTEM_UI_FLAG_FULLSCREEN
}