Gotta start somewhere and establish a list of references and a portfolio of past projects. The alternative is LinkedIn and wait for a recruiter to offer you a contract while they take 50% of the hourly rate. It's a really bad time for contracting.
Upwork and Freelancer are cesspits. Filled with people that don't bother reading your job and just spam your job listings. I'd sooner cold email startups asking if they need help (as annoying as that is).