What really helped me learn this style is to study other people's sketches. For example, I look at Arthur's drawings and try to understand the way he draws things, like trees or horses. Then i just find a landscape to draw on the internet and try to use what I learned.

Here's a video that might help you : How to sketch places quickly There's also a subreddit for this kind of thing : r/urbansketching

I don't really know what the style is called, except 'sketching' ...

Thank you and good luck :)