Satu, you definitely can change the look of your quilt with thread, even some thread painting, but you also want to be careful that you don't make everything blend together.
Maybe you can use some of your scrap fabrics to try out thread colors to see what works best to achieve the look you want.
Here is a photo of "Sugar and Spice" by Renae Haddadin. This quilt is one solid piece of black fabric on one side, and a solid piece of white on the other. The entire design is done with thread:
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