Before spending on bigger art, test it with the new light. Put a paper outline on that back wall, then look from the doorway and sit in each chair: a wider pendant could hide the part of the picture you like most. Recheck after deciding whether to turn the table. That costs nothing and gives you a firmer size to shop for.

I'm with PaintFu. Our dining-room art guide shows that seated-view/pendant check and how to plan around changing table layouts: https://www.paintfu.com/blogs/news/dining-room-wall-art-size-style-placement-guide

I'm not a fan of MCM decor, but if you are, and

you want to meld that style with your farmhouse table and Windsor chairs, I don't think you want to go too far to the "modern" style with the light fixture. Instead of the super glassy/sputnik styles shown above, a variation on a simple drum shade could work better.

Agree with everyone that the back-wall art should go bigger. That wall section looks roughly 5 ft wide, so a piece around 36–40" wide (or two tall pieces side by side) would fill it in proportion. Center it on the table rather than the wall, so decide on turning the table first. If you love the landscape you have, reframing it with a wide white mat and a larger frame can nearly double its footprint for little cost – tape the new size on the wall with painter's tape before committing.

To size a chandelier for your dining room, or to be the focal point of your space, measure the length and width of the room and add those figures together. The sum, converted to inches, will equal the diameter that you can use as a guideline when selecting the size of your chandelier. Example: 14' + 20'=34' Converted to inches = 34" Correct Size Chandelier=34" Diameter. If the resulting measurement (room length + width, converted to inches) seems inappropriate due to the size of your table, size your chandelier three quarters the width of your table.