If an autistic child has restrictive and repetitive behaviours around eating, it is easy to assume, "oh that's just an autistic thing" or" this is an anxiety/sensory sensitivity thing". However, autistic sensory experience is not simply quantifiable (more or less sensitive). It is likely to be quite different in many unique and beautiful ways.
Let's imagine a child has a cucumber cube. We see that they are examining it meticulously and searching for a specific surface before putting it in their mouth. Human prefers their food presented to them aesthetically, enhancing the experience of eating. (There is a Brain Child episode on Netflix on the topic.) This child may be experiencing food differently than a neurotypical person would, and eating with a specific shape and look enhances the experience of eating that cucumber.
Never treat avoidant restrictive food intake disorder (ARFID) without consulting a specialist in chewing and swallowing mechanics.
Additionally, it is important to comprehensively assess the autistic child's dining experience from the sensory/aesthetic perspective and as well as involving a specialist for chewing and swallowing. When we rush into exposure therapy without considering these types of factors that may be contributing to the children's eating difficulties, the child's improvement may not be transferable outside the clinical environment or sustainable in the long term.