ant-design/components/tree-select/demo/suffix.tsx

import React, { useState } from 'react';
import { SmileOutlined } from '@ant-design/icons';
import { TreeSelect } from 'antd';

const icon = <SmileOutlined />;
const treeData = [
  {
    value: 'parent 1',
    title: 'parent 1',
    children: [
      {
        value: 'parent 1-0',
        title: 'parent 1-0',
        children: [
          {
            value: 'leaf1',
            title: 'my leaf',
          },
          {
            value: 'leaf2',
            title: 'your leaf',
          },
        ],
      },
      {
        value: 'parent 1-1',
        title: 'parent 1-1',
        children: [
          {
            value: 'sss',
            title: <b style={{ color: '#08c' }}>sss</b>,
          },
        ],
      },
    ],
  },
];

const App: React.FC = () => {
  const [value, setValue] = useState<string>();

  const onChange = (newValue: string) => {
    console.log(newValue);
    setValue(newValue);
  };

  return (
    <TreeSelect
      showSearch
      suffixIcon={icon}
      style={{ width: '100%' }}
      value={value}
      dropdownStyle={{ maxHeight: 400, overflow: 'auto' }}
      placeholder="Please select"
      allowClear
      treeDefaultExpandAll
      onChange={onChange}
      treeData={treeData}
    />
  );
};

export default App;