I don't know the neurological mechanisms behind autism, but I know that ADHD is, briefly, defined by a reduction of dopamine receptors across your brain.

The brain is neuroplastic, especially when young, but I doubt you can just influence the growth of significantly more dopamine receptors out of pure willpower and habit-forming; especially given that ADHD disrupts those two facilities.

This is in part why dopaminergic drugs such as Adderall work so well, and why dopamine/reward-center disruption due to childhood trauma can have such a negative impact on one's ADHD symptoms.

Again, I don't know how much this applies back to autism, but it has definitely been a bane of my existence constantly explaining to people why I can't just meditate, habit-form or diet or exercise away my symptoms.

These things help, as does directed research and experimentation with what does and doesn't work for me, and because of my ADHD these things are integral to my ability to function as an adult in this insanely complex and stressful world. And it's definitely made a difference in how I manage my symptoms, especially when I look at how my siblings don't manage theirs and lack basic coping mechanisms.

But I frequently run into people who arrogantly assume I've never even heard of meditation, or that I have a bad diet, etc. and offer them up as panaceas. These people often get defensive and more arrogant whenever I try to explain to them that ADHD is not just some "mental block" or collection of bad habits that can be "fixed".

So yea... I also think we need to do way more clinical studies about the effects of teaching coping mechanisms at a young age, but I don't think autism is something that you can grow out of, there are likely specific underlying genetic and neurological factors that affect how much a specific individual can control or cope with their symptoms.