Answer:
The effect of the extended metaphor in the passage is that it sustains the comparison of death to night
Step-by-step explanation:
"Do not go gentle into that good night" by Dylan Thomas is a poem that talks about death, more precisely the narrator is waiting for his father's death, and as he makes the metaphor of night with death he tells the reader in these lines to do not accept death easily, to fight against it and not to go to the good night as it comes.