The sideboard looks small. Is it the picture/angle?

Art is personal and subjective. It should be bough because you love it and not because it matches the wall paint color, a throw pillow. or anything else.

Visit local art galleries and art/craft shows to start getting a feel for the type of art you might like.

I agree with replacing your current petite sideboard with a longer and perhaps talker sideboard.

A large piece of art over the new sideboard will be a great addition. Pick a personally-meaningful piece or upload a picture of your room to a web art site so you can virually try out different pieces.

A huge barnboard whale. It just showed up in my feed and thought it was interesting.

You need a large piece of art and it is going to make your sideboard feel like dollhouse furniture. Find a large piece of art you love. Taste is wayntoo subjective for anyone to suggest what you would love. Then get a new sideboard for beneath.

The other option is a mirror that will reflect light from your windows. But not just any mirror, because who wants to look at themselves in a mirror while eating! I’m thinking a paned mirror with beveled edges on each pane that gives enough distortion. But only if you like the paned mirror style…

I agree that your sideboard looks undersized, although it could just be the picture. One way to make the sideboard seem bigger would be to move the table end arm chairs to either side of it.