The way I learn is by building personal projects with a stack I know but changing out one technology for one I don't know. For example:
You're good at PHP, Django, MySQL. Then switch out the PHP stuff and write it in ReactJS. Write an application that is not too difficult and only uses the basics of React, then once you're comfortable, add some more features to the application that require you to use more advanced React. Keep going until you're comfortable using React (you don't need to know everything about it, just be comfortable building a somewhat advanced application). Then, switch out MySQL. Perhaps use MSSQL instead, or add a MongoDB alongside.
This is the way I learn new technologies. I hope it will help you as well.