I made this landscape today. And this I did with Illustrator software. I got the idea to make this from Pinterest. Moreover, I have given a link here, if you go there, you will find many such landscapes. However. The whole landscape is not really visible here. Because here I have clipping masked the landscape to a shape of a human head.
Below I have given some pictures of it, you can understand it better. After clipping mask I added some parts to it because the shape of the head didn't look like a mountain so I'm doing this to make it look nicer. The climbers are two I got from Freepik. And I made the rest of the sunset scene. Here are some pictures of how to make it. Hope you like it.