You could do some color on the ceiling, and/or art on the wall.

I think all it needs is a nice piece of art on the blank wall to the left. Either one larger piece or several smaller pieces would be preferable for proper scale. We can't really advise you on what kind of art since everyone's likes and dislikes are so personal. If it were me I would look for a large horizontal painting with some of my favorite colors in it.

Will you be adding curtain panels and/or a rug for softness and texture?

That is a modern or art deco molding profile. The current light fixture doesn't go with it at all, so I'm glad you've already addressed that, but I don't have a good picture of what the new fixture is going to look like. It would also help if we knew how you have decorated the rest of your house, or at least the adjacent room. Modern rooms are usually pretty minimalistic, so if that's your style, just get a large piece of dramatic art. You don't even need to paint. If your style is something else, let us know.

Unless you dislike having a rug under your dining room table, a rug really helps to bring color and style to a dining room. Also, do you like subtle color or were you thinking about doing something moody or dramatic?

I love freedomplace's idea of painting the ceiling in a color picked up from a large art work. How wonderful! Can you show us the light fixture you have planned to get an idea of the style and size? A large (or complementary pair) of abstract, semi-abstract, or realistic landscape depending on your taste, in greens and golden browns would echo the greenery outside your window, the wood floor and features, and give the feeling of another window.

Ceiling could be blue:

Tennessee Forest, Original By Alexis Baranek · More Info

Ceiling could be gold:

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Pairing of two art works below:

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la_la Girl, I feel like the ceiling is too low for curtains. I took the rods out that used to be there because they were touching the drop ceiling, it was not good…
I will definitely be adding a rug though! :)

This is a picture of the new dining room light fixture and living room furniture in the adjacent room. The dining room is to the left.

I'd put wallpaper inside the coved ceiling. Looks fantastic and will warm up the room. Then find a beautiful coordinating rug. A few examples:

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I painted the entire house white inside so that there was no competing colors to confuse things. I thought about adding accent walls but not sure what to do. My furniture is mostly traditional styles, overstuff leather couches, wooden tables, etc.

Art deco is making another comeback!!! Hooray; my favorite style, hence my handle "decoenthusiaste." Here is a color palette from Miami's AD preservation group. If you're not into the style, you could paint walls and ceiling both in the same color that delights you and leave the molding white. It's not unheard of to add color in the dining room, even in a white house.

LR colors, or DR?

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"Fallen Leaves Green Golden" by Cora Niele, Canvas Art, 30"x47" · More Info

Edgar Degas 'The Millinery Shop' Canvas Art, 47x35 · More Info

Some subtle colors -

Marilyn Hageman 'Classical Horse' Canvas Art, 35"x35" · More Info

"Ballerina Tan" by Paul Laoria, Giclee Canvas Wall Art, 30"x40" · More Info

27" x 18" Feather by PhotoINC Studio - Wall Art Print on Canvas Fabric White · More Info

"Dots" by Paul Laoria, Giclee Canvas Wall Art, 36"x36" · More Info

Love your Arts & Crafts furniture and embrace your ceiling detail. Consider Bradbury or William Morris wallpaper and colors. These sites are over-the-top, but you will get the idea. Paint or wallpaper the ceiling, Paint the molding a color and wallpaper the walls Here's some sites/pics for inspiration:

https://bradbury.com/centennial.html

or this: