I tried applying once for upwork but they have declined for a very silly reason "we have too many freelancers in the category you are applying, try applying to a different category".
What if those freelancers are not doing good job or providing poor quality jobs?
Anyway, I think freelancer site is much easier getting clients. So it's all about building good connection with your clients, making sure they are happy with your services. As soon as you complete one project, you can get another project with them and then give them a little higher pricing. The reason is because they really love working with you, they won't mind paying higher price for your services.
In my opinion, you need to establish your own agency out of upwork and start reaching out for clients without upwork as well in order to achieve your goal faster.
Wish you luck with your journey.