Visit UpWork, Toptal, Freelancer.com and some other websites.

Your best bets are on:
1. AWS Development
2. Mobile app development
  2.1 iOS Development - Learn Swift or Objective-C
  2.2 Android Development - Learn Java or Kotlin
3. Mobile & Website UI/UX Design & Research
4. Web Development:
  4.1 Front-End development
  4.2 Back-End development
  4.3 Full-Stack development
  4.3 React Development
5. Content Management
6. Data analytics
7. Software Engineer
8. Digital Marketing

But you can even monetize your non-it skills. For example, if you are into fitness, you can be an online coach and help people to achieve a good look.
If you are a gamer, you can stream your gaming sessions.

You can really monetize every skill you have if you are better than others in it.