Off topic, but interestingly, if lay arahant can live longer just by current action of ordaining, then this would have implication for their total old kamma to be used up.
Classical Theravada says infinite old kamma, cannot finish used up by arahant in last life, so no body or mind in parinibbāna means the rest of the infinite old kamma got defunct.
EBT have this AN10.217 which says no ending of suffering without ending kamma. AN 10.217 Paṭhamasañcetanikasutta
So let’s say a lay person got arahanthood is due to die in 7 days, their kamma would accelerate fast to ripen within 7 days. But got ordained within 7 days, suddenly got new kammas to support living more than 7 days as a result of actions done while an arahant? Or perhaps it’s just changing conditions made by arahant, which causes the remaining old kamma to be slower in ripening for longer lifespan rather than to jam-pack it all within a few days.
Or like Bhante Aggacitta would put it that arahant can still make kamma, like eating causes them to live longer. Just that the kamma doesn’t produce results for next life, only this life.