Learn the concept and experiment with it. You can follow a tutorial and recreate it by changing small bits. Then try to create something completely new. You can even try to implement the concept into another project. The idea here is to gain the needed expertise by practicing.
When you have enough working knowledge, write about it. It can be a blog post, Hashnode post or Medium post. Share your experience with other fellow developers. Give technical information and insight with code examples and demo repos. You will most likely get enough feedback to see if you really understand the concept or is there anything more to learn about it.
When you have a reasonable degree of understanding, try teaching it to somebody. Try answering questions here on Hashnode or on Stack Overflow about the concept. You can even find a friend or a colleague and explain it to him. If he understands it comprehensively, then you truly understand the concept.
If you can't explain it simply, you don't understand it well enough.
-Albert Einstein