Yes, the sentence:
Could you help me off the couch?
is correct as a polite request provided you close it with a question mark.
The verb help, just like other verbs like walk and drive, can take the pattern:
Verb + DO + adverbial particle/prepositional phrase
to indicate that somebody helps/walks/drives somebody else to get or go somewhere. This is, in my opinion, a remarkable example of the economy that characterizes the English language.