Tips on Dealing with an Autistic Child as a Non-Parent?
“Do you have any tips on dealing an autistic child as a non-parent?”

I am not sure if you are the child’s stepparent or if you are related to him in any way. In any case, my advice is that you educate yourself about two things.
First, learn about autism. Knowing about autism will make you feel more confident when dealing with this child. As in everything in life, information is power. At REC Parenting, we have a section on neurodivergent children with free resources. I also recommend the book “Differently Wired” by Deborah Reber. It is packed with evidence-based and practical information about autism and other neurodivergent conditions.
Second, no two children with autism are the same. Get to know this child. Learn what he likes and dislikes, what makes him happy and what makes him stressed, what he likes and hates to eat…
Finally, parents of neurodivergent children, such as this child you mention, usually find parenting much tougher. So, as much as you can, take care of them as well. Do not let them feel judged, accept their child as he is, and reassure them that they are doing a good job.
Related articles:
How to Support a 12 Year-Old with Autism and ADHD
How to Support Working Parents of Neurodivergent Children
I hope this information helps. I wish you all the very best.
Love,
Ana