What to learn next in DS to improve myself?

I already know:
Python > Anaconda, Jupyter Notebook, Pandas, NumPy, Matplotlib, scikit-learn
What to learn next to make a step forward to improve my data scientist skills?

Look for “data scientist roadmap 2019” on Google. You’re going to find a few path suggestions.

If you’re confident in your programming skills, boost your mathematics skills. If you’re confident in both, work on projects. You’ll find gaps in your knowledge along the way that you can fill as you go. You may find a specific area you prefer to focus on (databases, analytics, machine learning, information design, etc.) that you can then dig deeper on.

The best knowledge comes from practical application, so find some data and science it!