You would need to call your local office and see if they accept walk-ins without an appointment. See this IRS website to locate a local IRS office in your area - https://www.irs.gov/help/contact-your-local-irs-office
You should be able to search by your zip code and that will provide you their phone number and address. Most times, it will also state there if an appointment is required or not; and give you the option to make the appointment from there.