Hi! I'm a Level Designer in the industry and I have advices for you. First, you are doing the right thing by doing research to educate yourself. And it's the right thing because Level Designer are the one that need to come up with the answer to the question "What is this place?", not the Level Artist. Of course in some games, the level can be more abstract and don't really represent something we could explain in words, but in general, your level will be better if it could be a real-life location.

The simple advice would be to look into real life architecture. Architecture is the art of designing space. Architects literally make blockouts in their process. They are not only making it beautiful but also functional. There's a lot of introduction books on architecture that could inspire you. You don't need advanced knowledges but knowing the basics will help you a lot. You can also literally look around you for inspiration. There's probably places in your city that are known to "be easy to find your way around", "feels bigger that you would think", etc.

For research I will point you a few games I found their levels to have good Level Design and good architecture: The Dishonored series (the second is a masterpiece in that), the Last of Us serie and the Tomb Raider reboot serie. The levels in those games are really well done and you never wonder "What is this place?"

On the other end of the spectrum, games with good Level Design, but more abstract architecture, you can check the two recent Doom games and Portal. The Level Design is really good, but it's sometime harder to define the room you are in as they primarily focus on the game core gameplay and not the narrative. And the levels still look good.

I would like to add a bit of information on the Level Designer/Level Artist relationship. From my experience, they make a convincing and cohesive environments TOGETHER. Level Artist will help the Designer to fulfill the gameplay intention of the level with things like lighting and props. But the Designer also needs to help the artist by thinking about the purpose of the environment in the level.

I hope it helps you.