Some bands like Mastodon and GWAR just love shredding people's ears, but a lot of it will depend on the venue.
@Tom Cnyc can speak to the way stuff is usually mixed in the US but I think it's something like "98-105db" measured at the soundboard.
If you can find an
outdoor event where the artist is playing, that maximizes your chances of escaping worrying volumes. Personally I am fine at some indoor venues, but I'd never do another "noise band in a concrete box venue" type show (IE, the thing that boned my hearing).