There's lots of info on this site about aging. Dry aging is really for professionals with walk in coolers and temp/moisture control. I ask my butcher to age prime rib for 21-24 days for me and it makes an awsome roast.
Brisket wet aging - as said you need the kill date or packing date on the box. About 7 weeks from that date but that's in original cryovac. Now it needs a fridge that is dedicated to aging beef and storing meat. Temp controlled 34-35F and only opened once a week or so. The meat needs to be turned and you also need to look for bubbles. That's the start of gasses as the meat breaks down. Bigger bubbles = more break down. Quarter sized and you better cook right away and when you wash it after opening if it still smells then throw it away. I've had more than one brisket go in the trash when aging them.
Retired competition cook. BBQ mentor.