Working writers come in many different types. It can be pretty easy to lose perspective, as a writer. I have met writers who read all about it or followed a clear higher ed program and got into the industry that way: a steady day job version of being a professional writer. I have heard of a lot of them to.
The actual job description depends a lot on exactly which type of writer it is. Other factors, such as age and stage of life can also be very important.
There are brave and intrepid people in the real world who literally create their own jobs. Often, such people still work at other peoples’ companies, but they go to a business leader and sell themselves and the roles they have devised. I find that almost awe inspiring and daunting and I do not see myself as being someone like that. I am aware that some people can actually do that.
Others are even more wild and start businesses or change companies or found organizations and activities of that nature.
In such cases one can feel as if divination or a business degree maybe needed just to find out what the job description really is. Here are some fundamental basics: write and submit strictly to paying markets through editors, or else write, edit, work out a way to be published, then market and sell the published version of the works. Which is easier may depend on the individuality of the writer. Maybe none of it is. Maybe half the job comes easily but the other half is hard. Maybe a writer ends up having to do tasks to make it happen that had not been anticipated….Hadn’t realized it was in the job description.