Most incels are low T.
Staying around attractive females, being in positions of social power, good genetics and going outside a lot boosts testosterone.
99% of incels are not social moggers by default so that's already a habit that kills testosterone, and most incels also have other habits that kill T like poor diet and lack of sunlight.
T levels don't even matter it's genetics and nutrition/testosterone during puberty that gives you sexually dimorphic features, the only thing it's really good for is muscle growth and motivation. High T. is a risk factor for a ton of diseases too so not all good.
Studies demonstrate both high and low t levels so I don't think autism significantly impacts testosterone on it's own, it does result in neotenous and androgynous features in men which makes autistic people typically look less threatening and beta-like.