@Dayzea group
I did a lot of searching to find the proper kinds of websites to plot out books and do worldbuilding because, let's be honest, it's borderline impossible to be completely self-starting. Just going to share a few sites I found and what they can be used for ;)
storyplanner.com - This one is one of my favorites. You can only have one story saved with a free account, but you can always just copy-and-paste whatever you write into a document. There are tons of templates to assist with outlining your story, and it was phenomenally helpful for me to develop my stories, and even to realize if I didn't actually want to write certain ones.
hiveword.com - You can use this website to develop characters and outline scenes in your story! It's great if you have a good idea of what your story is going to be, but you need someplace to organize it. With a free account you can organize many stories and their characters, settings, items, chapters, scenes, and plotlines. The character outlines are really in-depth and great for summarizing. I wouldn't say this website is for stories still under development, though.
plotist.com - This website is a place for you to publish stories and also plot them out. With a free account, your outlines are public, though. Though it isn't perfect, it's good for beginning your outline and its outlining system is good for organizing multiple plotlines.
worldanvil.com - World Anvil would have to be one of my favorite sites for worldbuilding. Everything you make is public with a free account and you can only make two universes, but you can access many of the features of Notebook with in-depth descriptions. Essentially everything is here, and it's worth trying out even for just plotting. If the two-universe thing unsettles you, there are so many features that you can often just layer things in my experience.
writingexercises.co.uk - I don't even know, this one is just good for if you've got writer's block. There are a bunch of generators here and it can prove useful if you've hit a slump.
That's basically all. I mostly like to use notebook.ai to connect with other writers and to begin fleshing out my characters. I hope this was useful. Write on!