I want a docked bottom navigation bar in flutter

See I have two options for you here (potentially three):

1. Create a mix of bottom-navigation-bar and floating-action-button

floatingActionButton: FloatingActionButton(
          onPressed: () {},
          shape:
              RoundedRectangleBorder(borderRadius: BorderRadius.circular(15)),
          child: Icon(Icons.video_call),
        ),
        floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
        bottomNavigationBar: BottomAppBar(
          color: Colors.redAccent,
          notchMargin: 5,
          child: Row(
            mainAxisSize: MainAxisSize.max,
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              IconButton(
                icon: Icon(
                  Icons.menu,
                  color: Colors.white,
                ),
                onPressed: () {},
              ),
              IconButton(
                icon: Icon(
                  Icons.search,
                  color: Colors.white,
                ),
                onPressed: () {},
              ),
              IconButton(
                icon: Icon(
                  Icons.print,
                  color: Colors.white,
                ),
                onPressed: () {},
              ),
              IconButton(
                icon: Icon(
                  Icons.people,
                  color: Colors.white,
                ),
                onPressed: () {},
              ),
            ],
          ),
        ),

pseudo second:

Create a notch in the bottom-navigation-bar :

bottomNavigationBar: BottomAppBar(
          shape: shape: AutomaticNotchedShape(
        RoundedRectangleBorder(
          borderRadius: BorderRadius.vertical(
            top: Radius.circular(15),
          ),
        ),
        RoundedRectangleBorder(
          borderRadius: BorderRadius.all(Radius.circular(10)),
        ),
      ), // by adding this line in the above code
          color: Colors.redAccent,
          notchMargin: 5,
          child: Row(

2. Use Stack BottomNavBar Combo :

Stack(
            children: [
              Align(
                alignment: Alignment.bottomCenter,
                child: BottomNavigationBar(
                    backgroundColor: Colors.transparent,
                    items: const [
                      BottomNavigationBarItem(
                          icon: Icon(
                            Icons.home,
                            color: Colors.white,
                          ),
                          label: 'a',
                          backgroundColor: Colors.transparent),
                      BottomNavigationBarItem(
                          icon: Icon(Icons.search),
                          label: 'a',
                          backgroundColor: Colors.yellow),
                      BottomNavigationBarItem(
                        icon: Icon(Icons.person),
                        label: 'a',
                        backgroundColor: Colors.blue,
                      ),
                      BottomNavigationBarItem(
                        icon: Icon(Icons.person),
                        label: 'a',
                        backgroundColor: Colors.blue,
                      ),
                    ],
                    type: BottomNavigationBarType.shifting,
                    selectedItemColor: Colors.black,
                    iconSize: 20,
                    elevation: 5),
              ),
                      Positioned(
                        top: height * 0.25,
                        left: width * 0.40,
                        child: FloatingActionButton(
                          onPressed: () {},
                          shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(15)),
                          child: Icon(Icons.video_call),
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ],
          ),