For React, there exist a couple of living styleguide generators, like styleguidist, that take components, sass and some extra editable text and automatically generate a styleguide for a particular app out of this, depending on where the styleguide task is inserted into the build process, with every repeat of that process. Does anything similar exist for Angular 2+?
Caveat: I do not mean a coding styleguide, but a living styleguide that pretty much automatically documents layout (sass/css)styles, fonts, icons, colours, font sizes, and components with their parameters, amongst others. Those things happen to be called styleguides too, sorry about that, but I did not invent the name.
UI-jar is a drop in module that automatically create a living style guide based on the test you write for your components in Angular (2.x and above). A beta is available at https://www.npmjs.com/package/ui-jar
With UI-jar it's also possible to develop your components isolated, without the need of the rest of your app.
You also get documentation about your components.
Another option is Angular Playground. You have to write some code to define the scenarios that you want it to provide, but I've been using it on my projects and I like it.
If you want automatic UI component documentation, I'd go with Compodoc like yogibimbi mentioned in their comment.
It seems like there is a missing tool in the ecosystem that provides something like a combination of these two utilities.