Several times each year, the organization Project Homeless Connect hosts a day of service at the Bill Graham Civic Auditorium. Homeless folks come in to see dentists, opticians, DMV representatives (to get their state IDs), etc. Volunteers help with all of these things, accompanying the people as they move from place to place at Bill Graham, etc.
The next one is December 4. If interested in volunteering, here's the link: https://www.projecthomelessconnect.org/programs/daysofservice/