There are quite a few similar educational curricula around along the same lines as FCC, with small differences - some focus on Ruby/Rails, for example, while others may focus on Python as the back end of choice.
Will FCC make you a top-notch grade-a world-class master coder? Not in and of itself. None of them will. You will have to learn the basics, and apply the basics, and research a LOT. You will have to figure out how to synthesize the things you’re learning into something that makes sense to you, and you’ll have to flesh out the lessons with additional learning on your own.
It is a common practice, both here and on other online courses, to form study groups. Get involved with some, and use them to push yourself and others in the group to combine the various front-end components you’d like to learn (HTML/SCSS/TypeScript/React, say).
It is always suggested that, as you learn more and more of the basics, find github projects to connect with and contribute to. These will give you the opportunity to see how others are doing what you are wanting to do, and will allow you to connect to them and to develop your own skillset.
So the short answer is, will any online school turn you into Douglas Crockford? No. Only you can do that. Start learning, start pushing your limits, and start making something new. You can. The curriculum matters less, to my mind, than the intent and interest of the student.
with java? not so much. The backend of choice with FCC would be either Node, or (I think) python.