title: How to apply fontSize to CardHeader title in MUI?
body: <p>I want to change the title in <code>CardHeader</code> to 16px. I tried changing theme in App.js but it does not seem to work</p>
  <pre><code>const theme = createMuiTheme({
    typography: {
      useNextVariants: true,
      overrides: {
        MuiCardHeader: {
          titleTypographyProps: {
            variant:'h2'
          }
        }
      }
    }
  );
  </code></pre>
  <p>In the component:</p>
  <pre><code>&lt;CardHeader
    action={
      &lt;IconButton color=&quot;inherit&quot;&gt;
        &lt;MoreHorizIcon /&gt;
      &lt;/IconButton&gt;
    }
    title=&quot;Titletext&quot;
  /&gt;
  </code></pre>
  <p>The title font still does not change. What do I need to do to fix this?</p>