Till I understood your question you are trying to achieve this kind of ui.

This Link can help you to achieve the ui, there are various kinds of GUI available which can help you. I have added code which can also help to achieve the UI, hope it will work.

Plugin :
  awesome_drawer_bar: '<latest_release>'

AwesomeDrawerBar(
      controller: AwesomeDrawerBarController,
      menuScreen: MENU_SCREEN,
      mainScreen: MAIN_SCREEN,
      borderRadius: 24.0,
      showShadow: true,
      angle: -12.0,
      backgroundColor: Colors.grey[300],
      slideWidth: MediaQuery.of(context).size.width*.65,
      openCurve: Curves.fastOutSlowIn,
      closeCurve: Curves.bounceIn,
    )