I think pph and Upwork good when starting out as a freelancer just to help you build up a portfolio, especially if you are self taught. However, clients often only want to pay a pittance for work, moreso if you are a newbie. And the large associated fees and charges soon get disheartening.
I did for a while and it was useful to get me into a freelance mindset, but it is really hard to get work on there these days. I did copywriting, but find it much better to look for work in my professional field.