Although the title is generic, I think the OP is not talking about delays, but rather about an involuntary overnight transit (travelling A to B to C, when a lack of scheduled flights between B and C forces an overnight layover at B). This is most likely known at the time of booking.

I've only had to use this once, on a flight in business on AI where I was told by the TA who issued my ticket to go to the transit desk to collect my hotel and meal vouchers. But I would also like to get an answer to the OP's questions below.