title: MUI V5 styled(Typography) variant not work
body: <p>Right now the Typography variant is inline as below:</p>
  <pre><code>&lt;Typography variant=&quot;h6&quot;&gt;
    Any text
  &lt;/Typography&gt;
  </code></pre>
  <p>If the styled Typography writen as below, the <strong>variant</strong> does not actually take effect. May I ask why it does not work? How the code should be looks like? Thanks.</p>
  <pre><code>const StyledTypography = styled(Typography)(({ theme }) =&gt; ({
    variant: theme.typography.h6,
  }));
  
  &lt;StyledTypography&gt;
    Any text
  &lt;/StyledTypography&gt;
  </code></pre>