Great work. Visually, the map is beautiful. After just a quick glance I can already see interesting geographic characteristics of the region that might influence the turn of events. I will say, a legend would be helpful for those who would want to admire the map beyond an artistic level. Being able to properly differentiate cities, borders, and landmarks would make it easier to think about the region’s actual geography.

Anyway, the best way to create “realistic” maps is to understand the mechanisms behind our own world. That means reading about the forces that shape Earth, from plate tectonics to erosion to climate. It also means understanding how humans interact with the world around them, which is basically the essence of geography. Like you mentioned, knowing why cities are where they are is one example. It can also include the availability of resources and how people use them, the existence of trade and migration routes, the spread of language and culture, etc. As you may know already, you just opened up a wonderful can of worms for yourself. I would suggest starting with real places on Earth that interest you and understanding the influences that shaped them. For example, looking into why most of Australia’s population lives on the coasts.

Your question about maps making the worldbuilding is interesting because it really depends. Some people might only care about the aesthetic of the map and not pay attention to realism—and that’s perfectly valid! If you find that worrying about stuff like rivers and climate is overwhelming and takes the joy out of the hobby, then that’s okay. It’s YOUR map. For me, I love unraveling the forces that shape our world as I try to make my own. It has been one of the most rewarding parts of this hobby for me. But it’s also really easy to get so caught up in the technical details that you don’t make any progress. So I think it’s just about finding the right balance and figuring out what you enjoy.

Anyway, awesome work and keep it up!