I have heard some young people are able to get special education services until their early 20s? What exactly does this mean; is this just for those who need extended time to meet graduation requirements or are vocational and life skills services included in this? Can any person on a IEP get services until age 21 or is it just for certain categories or types of needs?

My daughter is 2E and stayed for an extra year after she met her graduation requirements.  She spent the year on a college campus and took a class per semester.  There was a sp ed teacher overseeing this - I think there were 6 in her group doing this.  The class & other on-campus services was 3 days per week.  The other days, she did a job shadowing program.  Her main area of need was social skills.  She was measured to be in the ~2nd percentile in 10th grade the one time they evaluated her social skills.  It's an IEP team decision about staying until age 21.  The program she was in was designed for students with autism but there are lots of other programs out there.

You need to have a need for the extra IEP services.  Again, it based on if the IEP team feels it's needed.