This is really on a person by person basis and it very much depends on what kind of autism you have out of all the ones on the spectrum. I have seen many in certain situations (guided living arrangement, own seperate apartments with occassional communal meals, to aid in social situation, kind of training/therapy thing). Most are not picky eaters at all, if it smells good it will be at least tried, and most will finish even if it's so-so. There is 1 fupamonster that is on her way to deathfat status (including type 2 and stache because fucked up hormones) that does not like to eat or even smell fruits and vegetables but will eat Gorgonzola whole, and she is the only one that is that bad. My cousin has classial autism and it will take time and effort to get him to try things but it is very doable. I think having to have a particular type of sippy cup or potato letter is a rare exception and not the rule by far.