Best foods/items for baby’s birthday party

Planning a first birthday party and want it to be nice of course, but I don’t have a lot of time to do a lot of planning and preparation. Expecting maybe around 75-100 people (large extended family) and was going to get costco pizzas, but what else can I get from Costco? Looking for recs for other foods (like frozen, easy to heat up etc), drinks, and other party supplies I can get all from Costco. Are the sheet cakes good?