Postgraduate prep school programs still accessible if I have already completed some college?

I am in a weird situation I suppose. I really wanted to take a gap year, but dove straight into college without weighing my options. I am autistic and college has been a very huge change for me. I already took one semester off last year when I started, and I recently found out about post-grad programs/the 13th year. I have emailed some different schools with this same question, but I will still ask here just in case any one knows. Will 13th year programs still take students if they have completed some college? I would be 20 by the time I entered, so is there an age limit at certain schools?

I suspect that your age will be the biggest barrier.

Dear OP @nohrdragon - agree with @Publisher that your age may be an issue…you could look at Landmark College program in Putney, VT. At least contact them, as they have a long and successful history of helping students with your stated background. There are a couple of colleges in Florida with dedicated programs for students with your background. Best of luck to you!