最终效果
点击 to test1

点击to test2  =>  to test21

点击to test2  =>  to test22

代码如下
 

          path: "page",
          element: <父组件 />,
          children: [
            { path: "test1", element: <Test1 /> },
            {
              path: "test2",
              element: <Test2 />,
              children: [
                { path: "test21", element: <Test21 /> },
                { path: "test22", element: <Test22 /> },
              ],
            },
          ],

父组件如下 

   import { NavLink, Outlet } from "react-router-dom";    

         <div>
          I am 父组件
          <div>
            <NavLink to="/en/page/test1"> to test1</NavLink>
          </div>
          <div>
            <NavLink to="/en/page/test2"> to test2</NavLink>
          </div>
          <div style={{ marginLeft: "80px" }}>
            <Outlet />
          </div>
        </div>

test1组件

import React from "react";
const Test1 = () => {
  return <div> I am test1</div>;
};
export default Test1;

test2组件

import React from "react";
import { NavLink, Outlet } from "react-router-dom";

const Test2 = () => {
  return (
    <div>
      I am test2
      {/* link */}
      <div>
        <NavLink to="/en/apply/test2/test21"> to test21</NavLink>
      </div>
      <div>
        <NavLink to="/en/apply/test2/test22"> to test22</NavLink>
      </div>
      <div style={{ marginTop: "60px" }}>
        <Outlet />
      </div>
    </div>
  );
};
export default Test2;

test21组件
​​​​​​​

import React from "react";
const Test21 = () => {
  return <div> I am test21</div>;
};
export default Test21;

test22组件

import React from "react";
const Test22 = () => {
  return <div> I am test22</div>;
};
export default Test22;