Yes, you can use web components in a react application. Even though many developers won't use this combination, it may require especially if you are using third-party UI components that are written using Web Components.
For example, let us use Vaadin
date picker web component as below,
import React, { Component } from "react";
import "./App.css";
import "@vaadin/vaadin-date-picker";
class App extends Component {
render() {
return (
<div className="App">
<vaadin-date-picker label="When were you born?"></vaadin-date-picker>
</div>
);
}
}
export default App;