19 years old and a senior in high school. Who graduates HS at 20?
‘Who graduates HS at 20?’
They are called an adult and it is a GED.
She won’t graduate. She will receive a Certificate of Attendance when she is officially overage and can’t stay in school. If she had been taken in hand by a more responsible adult relative at an early and homeschooled she would be ever so much better off, certainly more educated, and would function in the world at a higher level.