This is a regular landscape sketch! The so-called sketch is a sketch, which uses simple lines or light and shade to represent objects. The author of this sketch of architectural landscape has his own style: the lines are random and trivial. I feel like a master (the signature in front of the lower left corner is a little incomprehensible, maybe it is a master)! It seems to be painted with a gel pen, a signature pen or Gou Xianbi. If you want to learn sketch, many studios and drawing boards generally teach it, and there are also some college entrance examination training courses specially for college entrance examination art students. Some studio teachers may have similar styles. Learn from these teachers, and your own style will be inclined to this style. That is to say: what style of teachers do you learn from, and what style will you learn in general, especially beginners.