Judging by the author's signature, she or he used Procreate and drew on the iPad Pro 11" with Apple Pencil. I want to add that we should not forget about years of practice and interest in this activity. I recommend everyone to read https://paperap.com/free-papers/drawing/ and learn more about drawing, teaching methods and much more on this topic, I think you will like it and someone will definitely find this resource useful.
Develop your talents and share your achievements with the world, it's inspiring!