It's not worth it, people from developing countries basically dominate on those platforms, so you have to go cheaper than them, especially if you have no reviews
On Fiverr it's hard to get discovered
On Upwork you'd have to apply to tons of jobs, each application uses up one of the "credits", when you run out you have to buy more for IRL money. You might use up all of the free ones and still not get a single job.
The more people you know the more likely you are to find work.
Finding good clients is hard work, so anyone with good clients works hard to keep them.
Therefore, any easy way of finding gigs is mostly swimming in an ocean of not-good clients.
Good luck.
I've done some research but thought I'd ask someone that might have experience.