I'm a content strategist, so this is what I spend the majority of my time on. I can explain my role on my team, if that would help.
I work for an agency that makes mobile apps. We have about 12 designers, who are extremely well rounded: they all are expected to do visual design, interaction design, information architecture, motion design, and content design (ie, writing).
I came aboard last August. Now that I'm here, I handle content-heavy tasks such as managing content matrices and content modeling. However, since those tasks don't come up all the time, most of my time is really spent consulting with designers who have questions about interface content: what should this error message say? Which call to action is best? How can we onboard the user in 35 words?
It's very difficult to completely separate writing from UX. (If you read Steve Krug's Don't Make Me Think, a lot of his usability findings center around words and content.) So I see this as a collaboration between writing and design (which is why I like the term content design).
Does that help? Let me know if you have any questions! I love talking about content strategy and UX.