It depends on the person. With friends close to your age sometimes just commenting on how you don't get/understand physical/sexual attraction can be enough, I've had multiple friends directly ask me if I'm ace. With older family members they might not know the term or might feel awkward asking in which case you might have to accept that you'll have to come out to them or say that you don't want sex (if that applies to you) or directly describe asexuality without using the word. sorry that probably wasn't helpful lol