When the narrator visits Father Flynn’s home after the priest has died, he reflects on his interactions with the priest in the past, using a hyperbole in the process:
Had he not been dead I would have gone into the little dark room behind the shop to find him sitting in his arm-chair by the fire, nearly smothered in his great-coat. Perhaps my aunt would have given me a packet of High Toast for him and this present would have roused him from his stupefied doze.
The hyperbole in this passage—in which the narrator describes how Father Flynn would sit by the fire “nearly smothered in his great-coat”—uses exaggerated language in order to communicate how unwell the priest was in his final days. He was likely in a “stupefied doze” while wearing a thick coat indoors by the fire because of either fever or severe physical weakness.
Joyce’s use of exaggerated language here is intentional. He wants readers to understand how ill and weak the priest was because the priest is a stand-in for the Catholic Church, an institution that Joyce hints is (morally) deteriorating the way that Father Flynn himself deteriorated.