If we're talking about writing only, like drafts. I can write 3000 to 5000 words per day. But that doesn't mean they are all good to publish. As a content writer myself, I struggled a lot with writing more words per day. At first, I was writing like 500 to 700 words a day. Now I write around 1500 to 2000 words max. Usually, more than 50% of my time goes into research, 20% time into writing the first draft, 15% time into rewriting, and rest of the time into editing, proofreading, Grammarly check, and plagiarism check.
A tip for new writers: if you're struggling with writing more words and stuck at a blank screen thinking you hit writer's block. No. The actual problem is — You didn't read enough on the topic. Put more time into research, and read more articles related to your work. The more you read, the more your brain congregates similar information to produce. If you don't know a topic well, how can you expect your brain to spit-out words?