UpWork is great to find a freelancing job, not so much the regular one.
My advice would be to focus on exactly one thing - be it React, React Native, or whatever else you like best.
For every job, you'll be competing with dozens of other developers and if you spread your time between React, game dev, machine learning, and React Native you'll likely lose with someone who devoted their whole time to only one thing.
Early in your career specialization is essential. You can develop in other directions when you have a job and get paid for learning to code.
If you'll decide to pick a frontend career (React / React Native) I just released a book that helps to find your first job - szadamiak.gumroad.com/l/frontendjob
And if you don't want to spend money I've got many articles with career advice on Medium (sadamiak.medium.com) or you can DM me with specific questions on Twitter - twitter.com/s_adamiak.