The wall of my living room is white, and the sofa is light purple. What color frame should I use to match it? Is it white, black, crimson or log yellow?

Black. A large part of your home is white and light beige, and black can echo the coffee table. Don't put the picture in the background of the sofa too big. 40-45 cm, 4-6 side by side. Simple color painting (such as a green square in the middle, which is the kind of high-end furniture in many TVs) or large abstract painting. Absolutely classic.