materialuiupgraded/packages/material-ui-icons/src/Maximize.js

Material-UI's workspace package

import React from 'react';
import createSvgIcon from './utils/createSvgIcon';

export default createSvgIcon(
  <React.Fragment><path fill="none" d="M0 0h24v24H0V0z" /><path d="M3 3h18v2H3z" /></React.Fragment>
, 'Maximize');