I wrote about this in my response to @LewishamMumNow but I'll cover it again.
People with autism can have interchangeable high support needs and low support needs throughout their entire life.
What people perceive as profound autism is usually high support needs autism with comorbidities such as developmental delays or learning disabilities, ie. The inability to learn to do things like learn to look after themselves either partially or fully, learn academically etc.
Autism alone covers 3 distinct areas of life, with which you have to meet all the criteria in order to receive a diagnosis.
Some people may struggle less due to the way in which they present on the spectrum however that does not mean that they will always struggle less.
Like all people, needs change over the years. People with autism may require more or less support as their needs change.
My son received a very early diagnosis himself as he very obviously presented with high support needs: heavily stimmer, non-verbal, did not respond to name or social cues, couldn't even bear the texture of sensory friendly clothes so spent the first 3 years of his life practically nude. Now he is able to speak, stims less, gets his needs met quicker and can meet his own needs a lot of the time, and is thriving in a mainstream school which I would not have imagined possible a year ago.
I however am almost 30, highly masked as a child, hyperlexic, had less obvious stims and was just deemed hyperactive and quirky, spoke extremely bluntly, scripted, struggled to make friends but I was just called a rude or naughty child, hyperfocused at school, couldn't hack the social requirements of college or university so dropped out, ended up at the job centre, got literally any job I could take which was call centre work, excellent with the structure however unfortunately they can't meet my needs and now I find myself unable to speak some days and am struggling with the long term effects of burnout and am extremely sensitive to all stimuli to the point I will rock back and forth crying and experiencing intense panic attack-like emotions. I can't take wet clothes out of the washing machine, I can't wash my pots, I can't stand the smells of food, lights give me intense headaches, all sounds make my blood curdle and I become extremely aggravated easily.
My support needs are higher than they were when I was my son's age.
So there's no such thing as mild autism. It's all bollocks frankly, and it's all dependent on the support and life experiences available and provided.