Theoretically yes
In reality he is very dyspraxic and his attempts to butter bread usually leave a slice of bread in tatters...and he's not great with a knife!
Day to day, he will do himself cereal for breakfast, and then will buy the exact same meal deal (wrap, yoghurt and drink) for lunch at work, and then whatever I have cooked for dinner. He works 'lates' most days so he doesn't always eat with us but I'll plate up stuff for him, and at least once a week he gets chips on the way home... not ideal but he's tall slim and reasonably healthy and while I'd like to police his food choices, he IS an adult!
He is a bit scared of hot things, and also would not remember to take things out of an oven (nor would it be safe) so 'proper' cooking isn't happening.
But having said that, he is still gaining skills. He's 26 now. In the last year he has started to remember to strip his own bed, put laundry on and in the dryer. He manages his own bank account, and I just occasionally check all is ok ... he is prone to being scammed and to contributing to ANY cause asking for money so I do keep an eye on that. We live literally a 2 min walk from his workplace so travelling there is fine, and he can take the local bus to town, but further afield he needs company, and he couldn't take a train, plane, go off on holiday etc, nor would we leave him home to go on holiday ourselves...he wouldn't burn the hosue down, but he might not notice if it was coming down round his ears!
His eldest sister IS high functioning... you wouldn't know immediately that she is on the spectrum ( you'd guess pretty quickly with my son). She is totally independent, has her own home and is a GP!! Can't drive (yet) as also dyspraxic but incredibly intelligent, kind and a good doctor. She has good friends.
BUT I'd say her life has been harder in many ways, her intelligence masks her crippling anxiety. Both of them are medicated for anxiety and OCD, which often goes with autism. She has ARFID and eating is an ongoing battle for her.
The thing with autism is, if you've met one person with autism...you've met one. Everyone is different. I work with severely autistic children..non verbal, sometimes very aggressive, and yet some blow us away with how the develop.. :)
Sorry, that was so long! But over 30 years of raising two children with autism (and two without!) and working in Special Ed , I know how much I have worried myself sick over my two, and how... somehow... things pan out ok. Maybe not how I imagined, but ok.
Of course I do have to live forever for DS2 but hey ho...