Look for stripes in the colors of the art work. ETSY isa great place for unique pillows.

Thank you

It looks like you are selecting solid color pillows Your sofa looks like a solid color, so go with some kind of print or pattern for pillows with some variation that pulls color from the art, keeping in mind that you may need to take some home that will surprise you. 2 pillows are plenty for the sofa. Try to find down-filled pillows; they will suit the sofa nicely and are more comfortable. Best wishes, Connie

https://www.thespruce.com/timeless-color-rule-797859 Use the 60 30 10 rule to decide which colour to add, and how much. Consider the whole room not just one piece of furniture.

If it were me, I would go with a pair of creamy simple pillows with dramatic texture -

FWIW slick, hard tabletops look great when texture can be added to the top - contrast flatters them both, i think adding textural items to your tablescapes would elevate the room a bit - love your art over the sofa!

If the hot pink book is a part of your coffee table decor, repeat the colour in pillows etc until you have 10%. If it just happens to be there, get a book cover LOL. Its brightness draws the eye from everything else in the room.

If you delete the hot pink, then repeat the colour of the glass balls until you have 10%.

Your coffee table decor is busy. It would look better with decor items either on top of the glass, or on the lower level, but not both.

Your lamp would look better with a much larger shade, and lower. Its tall narrow proportion is wrong for an end table. It is a buffet lamp, most often used in pairs on a dining room buffet.