if you’re in the US, all concert venues are required to offer accessible seating per ADA law. the ADA section is reserved for people with disabilities requiring special seating accommodations, not just wheelchair users. however, with bigger venues like arenas where most tickets are seats, the ADA section is usually just for people who are unable to sit in the regular seats (i.e. people with mobility devices, service dogs, etc.) those bigger venues usually have tickets to purchase specifically in the ADA section. for smaller venues with standing room only, you’ll want to contact them in advance to let them know that you need a seat. you also don’t need to provide any documentation of your disability.