Using light sources is important to get the 3D Render view looking its best. You don’t need to spend a large amount of time to get decent effects.
The lights are setup initially in the File – Setup – Render Lighting… area. There are three light types. Directional, Point and Spot. Directional light would be like Sunlight. It shines from afar. Point light is a source that radiates in all directions. Spot lights can be focused. All the light types can be modified after they are placed in the room.
Here is a view with the default lighting. It looks OK but it could use some enhancements.
This floor plan has a Directional light that was modified in direction and angle.
You can see that more light effects would be useful.
2 Point lights were added at opposite sides of the room.