Scrivener.It is $23 on IOS. $60 on Mac & Windows. If you have a Mac or a Windows' laptop, there is a way to 🏴☠️ and I can tell you how. I have had it for months now, and it is a lifesaver for messy writers like myself. If you want to know, please, add me on discord (frailweb) or twitter (bvcktick).
It is great for organizing everything. I have so much notes, research, outlines, etc. I love folders. You can also use it offline.
If you don't have a laptop, I also use Google Docs and I organize my documents & folders like:
[Book name] Outline/Draft/Notes (Date)
If you want to use scrivener, this is how I organize everything. I can make a template.All of my bookmarks I have for my research. You can also open it in the app!
Pages
It comes with the IPhone, has folders as well, etc.
Zoho Writer
There is a new site called Ellipsus! It has folders, collaboration, etc.
I would rec more apps, but I do not use them, there's no good writing apps for organization and if they are it's expensive as hell.