It's just not realistic to hope/expect a total stranger to be interested in donating hours and hours of their time for free on a project they have no connection too, and no reason to expect profit from.
The best way is to work hard and save money to pay an artist.
Otherwise, work hard at the craft of writing, and consider seeking an artist to collaborate on a short one shot. If someone was going to donate free time, it's way more likely to be on a project that could be done in a month, rather than indefinite years. Assume a minimum of one week per page (five panels).
But still, think carefully about how you'd feel if a total stranger wanted you to spend 10-20 hours a week working for them with no pay. How would you feel having your labor and time valued so little?
Edit: also want to add in good faith, I checked your previous post in collaboration, and you really never even explain what your story is about. A list of anime you like is not a pitch. You should take the time to clarify what your story is without referencing anime or other properties. Who is the protagonist? What is the conflict? What is the content of this story?