App.tsx

    import ReportDesigner, { RequestOptions} from 'devexpress-reporting-react/dx-report-designer';
    import 'devextreme/dist/css/dx.light.css';
    import '@devexpress/analytics-core/dist/css/dx-analytics.common.css';
    import '@devexpress/analytics-core/dist/css/dx-analytics.light.css';
    import 'devexpress-reporting/dist/css/dx-webdocumentviewer.css';
    import 'ace-builds/css/ace.css';  
    import 'ace-builds/css/theme/dreamweaver.css';  
    import 'ace-builds/css/theme/ambiance.css';  
    import '@devexpress/analytics-core/dist/css/dx-querybuilder.css';
    import 'devexpress-reporting/dist/css/dx-reportdesigner.css';

    function App() {

      return (
        <ReportDesigner reportUrl="TestReport">
            <RequestOptions host="http://localhost:5000/" getDesignerModelAction="DXXRD/GetDesignerModel" />
        </ReportDesigner>       
      )
    }

    export default App