If it were me, I would sever the pillow in several places to make the size throw pillows you want on your couch. Then I would find material that will accent and bring out the accent colors of your home. For example, we have a lot of sage and dark brown surfaces so I would lighten them up with some brighter colors of red/orange/yellow in floral or geometric prints with small brown or sage amounts too. This would tie it all together. If you sew, this is a simple task. You could even hand sew them if you prefer and glue the outside colorful material over them. If it were me, I would sew them and sew in a zipper or overlay so they could be removed and washed. Hope this helps Kathy!
Unless the back of your sofa is low, the king size plllows will be too narrow. Best to get some of the square Euro pillows that are much bigger for a sofa pillow.
videos https://www.youtube.com/watch?v=n6cVGFudILs another https://www.youtube.com/watch?v=DtiEgnupR5U covers https://www.youtube.com/watch?v=f3KwIjNAsCA another https://www.youtube.com/watch?v=qIJl1ps7eyc no sew covers https://www.youtube.com/watch?v=XY6eqTYVQXU more no sew https://www.youtube.com/results?search_query=DIYno+sew+pillow+covers
A well fitted pillowcase with the open end tucked in is an easy no-sew method.
Cut the pillow in half or make small pillow covers and fill from that big pillow