In this example, we'll have text inputs, a textarea, radio buttons, a checkbox, and a dropdown/select field. The submitted data will appear on the webpage. Remember, this is just a basic example, and you can change it to fit your needs.

import React, { useState } from 'react';

const ComplexForm = () => {
  const [formData, setFormData] = useState({
    firstName: '',
    lastName: '',
    email: '',
    password: '',
    bio: '',
    gender: '',
    agreeTerms: false,
    country: 'Select Country'
  });

  const handleInputChange = (event) => {
    const { name, value, type, checked } = event.target;

    setFormData((prevData) => ({
      ...prevData,
      [name]: type === 'checkbox' ? checked : value
    }));
  };

  const handleSubmit = (event) => {
    event.preventDefault();
    // Access form data from formData state
    console.log(formData);
    // Perform form submission action (e.g., send data to server)
  };

  return (
    <div>
      <form onSubmit={handleSubmit}>
        <label>
          First Name:
          <input
            type="text"
            name="firstName"
            value={formData.firstName}
            onChange={handleInputChange}
          />
        </label>

        <label>
          Last Name:
          <input
            type="text"
            name="lastName"
            value={formData.lastName}
            onChange={handleInputChange}
          />
        </label>

        <label>
          Email:
          <input
            type="email"
            name="email"
            value={formData.email}
            onChange={handleInputChange}
          />
        </label>

        <label>
          Password:
          <input
            type="password"
            name="password"
            value={formData.password}
            onChange={handleInputChange}
          />
        </label>

        <label>
          Bio:
          <textarea
            name="bio"
            value={formData.bio}
            onChange={handleInputChange}
          />
        </label>

        <label>
          Gender:
          <div>
            <label>
              <input
                type="radio"
                name="gender"
                value="male"
                checked={formData.gender === 'male'}
                onChange={handleInputChange}
              />
              Male
            </label>
            <label>
              <input
                type="radio"
                name="gender"
                value="female"
                checked={formData.gender === 'female'}
                onChange={handleInputChange}
              />
              Female
            </label>
          </div>
        </label>

        <label>
          Agree to Terms:
          <input
            type="checkbox"
            name="agreeTerms"
            checked={formData.agreeTerms}
            onChange={handleInputChange}
          />
        </label>

        <label>
          Country:
          <select
            name="country"
            value={formData.country}
            onChange={handleInputChange}
          >
            <option value="Select Country" disabled>
              Select Country
            </option>
            <option value="USA">USA</option>
            <option value="Canada">Canada</option>
            <option value="UK">UK</option>
          </select>
        </label>

        <button type="submit">Submit</button>
      </form>

      {/* Display submitted data */}
      <div>
        <h2>Submitted Data:</h2>
        <p>First Name: {formData.firstName}</p>
        <p>Last Name: {formData.lastName}</p>
        <p>Email: {formData.email}</p>
        <p>Password: {formData.password}</p>
        <p>Bio: {formData.bio}</p>
        <p>Gender: {formData.gender}</p>
        <p>Agree to Terms: {formData.agreeTerms ? 'Yes' : 'No'}</p>
        <p>Country: {formData.country}</p>
      </div>
    </div>
  );
};

export default ComplexForm;

This example has different input fields and manages their changes. The submitted data shows up under the form for checking. Change it more to fit your needs.