How about showing the entire kitchen and area in general.

IMO go on Art.com and find a piece you love I never advise my clients about art it is not my choice what you love, These were the choice for this clinets kitchen she loved them we I kind of used them for a accent red tile wall on the wall opposite

I just wasn’t sure if I should do one piece vs. 3 pieces and if I do one piece should it be rectangular or square. Thank you for your response 😊

How tall are the ceilings? You might have better luck covering that area with a group of four. Use painters' tape to outline the area you want to cover and then start looking for pieces that fit the bill. Don't hang anything too high. Whatever it is, it needs to relate to the table and chairs and not look like it's floating over them by itself.

I don’t think one piece (no matter the size) will feel well balanced due to the length of the wall and the small table. To get a sense of scale/placement, use kraft paper and test different arrangements, but three across might be a good choice. Error on a larger size vs too small.

Choose art that you like, it's very personal...

From what's visible in the picture, the floor seems fine. It's not a good tonal contrast with the wood baseboard. Painting the baseboard the same color as your doorway trim would be a small project that makes a big difference.