Of course, couplets can be posted in the house. Nave's paintings are generally accompanied by couplets, and good words can also be appreciated as calligraphy. Many people still post couplets in their study, and rural people have couplets in almost every living room (rural elderly people are more particular than us).
As one of the traditional cultures in China, couplets are antithetical sentences written on paper and cloth or engraved on bamboo, wood and columns. The antithesis of couplets is neat and even, which is a unique art form of Chinese language and a treasure of China traditional culture.