Freelancer sites such as
http://www.xbtfreelancer.com/ that pay with bitcoin are vanishing nowadays because of too much of scams, I was a member in xbtfreelancer.com since it's inception but later on in the year 2017 they stopped new signups and in the year 2018 they stopped their operation, in my recent study all those freelancer websites that accept bitcoin as a payment method where closed their operation. So trying to find such websites won't help you a lot.
My best suggestion to earn bitcoin is to learn how to trade bitcoin and do it yourself after you think you are an expert, because crypto trading is very hot and works forever. If you want me to suggest crypto trading courses I can help you.