Prepositional phrase modifying a subject at the end of a sentence

I want to express I was sitting on the couch watching TV. I heard that “I was watching TV on the couch” makes sense. I think a prepositional phrase at the end of a sentence can act as a subject complement, but I also want to know a prepositional phrase at the end of a sentence can act as an object complement at the end of any sentences (not only “treat” or “consider”).