title: How to increase on the size of the leading icon off an AppBar flutter
body: <p>I am looking for a way of increasing the size of  Appbar leading Icon. Below is my code 
  :</p>
  
  <pre><code>appBar: PreferredSize(
                preferredSize: Size.fromHeight(120.0),
                child: AppBar(
                  leading: SizedBox(
                    width: 200,
                  height: 200,
                  child: IconButton(
                    padding: new EdgeInsets.all(0.0),
                    icon: Image.asset('assets/app_logo.png', height: 700.0, width: 700.0,)
                    ,
                  )),
              centerTitle: true,
              actions: &lt;Widget&gt;[
                IconButton(
                    icon: Image.asset('assets/path.png'))
              ],
              bottom: TabBar(
                  labelColor: Colors.white,
                  indicatorColor: Colors.lime,
  
                  tabs:[
                    Tab(icon: null,text: 'RECENT',),
                    Tab(icon: null, text: 'TOPICS',),
                    Tab(icon: null, text: 'AUTHORS',),
                  ]
              ),
            )
  </code></pre>
  
  <p>From the code above, specifically the size I implemented is below, but it couldn't work :</p>
  
  <pre><code>child: AppBar(
                      leading: SizedBox(
                        width: 200,
                      height: 200,
                      child: IconButton(
                        padding: new EdgeInsets.all(0.0),
                        icon: Image.asset('assets/app_logo.png', height: 700.0, width: 700.0,)
                        ,
                      )),
  </code></pre>
  
  <p><strong><em>My goal is to increase the Right top icon more bigger, but it doesn't increase it's size.</em></strong></p>
  
  <p>The screenshot is as below :</p>
  
  <p><a href="https://i.stack.imgur.com/xfKYD.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xfKYD.jpg" alt="enter image description here"></a></p>