Most of this is obvious once somebody says it, which is the problem with it not being written down anywhere.
They will ask for these
Photo ID
Insurance card
A list of your current medications. Doses too, not just the names. You can write it below.
Your ride's name and phone number. Written down rather than remembered. Not having a named driver is the most common reason procedures get canceled on the day.
Copayment
Wear, or bring to change into
Loose, comfortable clothes. The air used during the procedure leaves most people bloated for a few hours, so anything tight around the middle is uncomfortable.
Warm socks. Procedure rooms are kept cold, and a gown does not help.
Shoes you can slip on. Sedation makes laces more difficult than they should be on the way out.
Glasses rather than contacts. Contacts have to come out before sedation, so it is simpler to arrive in glasses.
A hair tie, if you need one
For the waiting
A long charging cable. Waiting room outlets are never next to the chairs, and a short cable means sitting on the floor by the wall.
A battery pack. Visits often run to a couple of hours, which is longer than a half-charged phone lasts.
Headphones
Something undemanding to read or watch
Quietly worth having
Chapstick. A day of clear liquids is drying, and lips notice first.
A spare pair of underwear. This is rarely mentioned and occasionally needed.
A snack for the ride home. Vending machines are usually the only option between the office and home.
A tote bag. You leave with discharge paperwork, your clothes, and whatever you brought, usually in a plastic bag someone hands you. A tote is one less thing to juggle while sedated.
Leave at home
Jewelry and anything valuable
Nail polish, on at least one hand. The clip that reads your oxygen needs a clear nail.
Any plan to drive yourself. They will not let you, and they do check.