You have both the floor lamp and the plant on one side of the sofa. One of these items should move to the other side, probably the floor lamp.

I suggest a vertical format for your art to take advantage of the room height.

I have changed the color of the base pillows on the sofa

Added a rug to anchor the area.

You can certainly go darker with the walls. However, then I would add a lot more white and lighter colors for the pillows and accessories. Also add reflective surfaces if that goes along with your style. You can do that with glass table tops and wall mirrors. A note about lighting: darker walls also means more lighting. The best for a living room is a table lamp or wall sconce in each corner at chest height. Below is a link for a similar (yet taller) art piece for your wall. If you just want to get the print and frame it locally, that's what I do. Since you have such a neutral palette, you can certainly pick up more blue from your wall art. I agree with the other poster to use that blue for the pillows and rug.

https://www.art.com/products/p48762544151-sa-i10969553/laurie-fields-coastal-hues-ii.htm?upi=F9908T0&sOrigID=1833