Julie here from Shopify Support.
If you want to hire someone to write your product descriptions, I suggest hiring a Shopify Expert. In fact, there are plenty of Shopify Experts skilled in copywriting who would be happy to help you out. Feel free to get in touch with a couple of Experts directly for quotes.
If you decide to write your own product descriptions, I recommend checking out our blog post, 9 Ways to Write Product Descriptions that Inform and Persuade Your Customers. There, you'll learn how to write effective product descriptions and will discover some excellent tips and examples. It might be worth checking out!
I hope this helps!