Sensory issues are not one of the features of the diagnostic criteria for Autism, but they are frequently reported and clinicians specialising in Autism diagnosis rarely discount them. It's not certain if sensations are actually different for Autistics than for non-Autistics; there's no way of really telling, but it appears that Autistics process input differently. So no super-hearing or bloodhound sense of smell, it's just that whilst Autistic senses pick up exactly the same stuff as anyone else, a different set of filters are applied to it.
This demo of an educational game about Autism has been doing the rounds. I can't endorse it but I'm reluctant to criticise it. Do I say "It's accurate/inaccurate"? Do I say "It works as a metaphor"? I can't be sure of any of those, but when I watched it my feeling was "This seems familiar". And it is- it is how I remember the school playground. I can't be sure if it is definitely how I experienced it back then, but it is familiar with that time and place. That leaves one explanation for my uncertainty about it; it isn't a complete view on 'my world'. It is not just crowds being sensory hazards, with no feeling of life to them. The scene plays out in a way that explains the overriding primary concern to seek safety but not what the experience is like when that is achieved other than the absence of distressing input. Maybe part of the problem is that the player controlling here isn't 'behaving autistically'; they stay at the edges and get away from people, but there is no exploration. An Autistic child will self-stimulate(stim), they'll look at how they can manipulate their vision, how things lose shape and colours change; all observations that can only be made in the first-person. An Autistic child on their own can seem indistinguishable from others, but when they are near other children they might not choose to escape but to explore these things and that's when they really stand out.
Some people literally 'see' colours or 'hear' smells and when this happens it's called synaesthesia. Vincent Van Gogh is rumoured to have experienced this, giving things he saw a 'feeling' of texture that he attempted to convey in his painting. He is not often speculated to have been Autistic though; synaesthesia is not exclusive to Autism. But even for Autistics that do not literally get senses crossing over, there is an experience of texture for things that are being seen. It could be an exaggerated form of association: hard things have a distinctive noise when impacted, bouncy things tend to make two sounds close together, so it could be that the extra details that get through an Autistic person's sensory filters lead to more associations.
These are frequently wonderful. The other day there was snow during sunset, the clouds dropping it from directly above whilst the sun was between the cloud and horizon with the blue sky behind it. I felt I was absorbing all of it- contrasts both stark and subtle, the way they changed, snow creating shimmering shafts of light and it being blown along the ground, up walls and over roofs like it was a river of smoke. When a simulator is able to convey that as well as what's in the video, then Autism will be understood. Mostly.
I can't even begin to explain how this all affects my emotions without any external input at all.