title: MUI V5 Variant Overrides
body: <p>I'm trying to add to the variant within MUIPaper and I'm not sure what I'm doing wrong. The types on the component are:</p>
  <pre><code>variant?: OverridableStringUnion&lt;'elevation' | 'outlined', PaperPropsVariantOverrides&gt;;
  </code></pre>
  <p>How do I extend the variant prop using PaperPropsVariantOverrides. My expected outcome is:</p>
  <pre><code>variant?: 'elevation' | 'outlined' | 'grey' | 'white',
  </code></pre>
  <p>Component: <code>Paper.tsx</code></p>
  <pre><code>import React from 'react';
  import MUIPaper, { PaperProps as MuiPaperProps } from '@mui/material/Paper';
  import { PaperPropsVariantOverrides } from '@mui/material';
  
  export interface PaperPropsVariantOverrides {
    variant: 'grey' | 'white';
  }
  
  export type PaperProps = MuiPaperProps;
  
  const Paper: React.FC&lt;PaperProps&gt; = (props) =&gt; {
    const { ...paperProps } = props;
  
    return &lt;MUIPaper variant=&quot;grey&quot; {...paperProps} /&gt;;
  };
  export default Paper;
  </code></pre>