I would start by looking at what the school he is attending provides for a list, and if you know their residental hall even better - some had dorm specific things that were provided or needed.
Our student had very simple needs - clothing, bedding, computer/electronics, shower/toiletries, laundry, cleaning supplies. I used this list
https://yourtimetofly.com/college-packing-list-for-guys-with-printable-pdf/ to give myself ideas and then had our student created their own list of items they wanted to bring with them (posters, pictures etc).