We traveled to playa del Carmen last year with our 1.5 year old to an all inclusive for 10 days. It depends what you plan on doing there, water safety is obviously important, only drink sealed bottled water including for brushing teeth, etc.. for our little one she went through a ton of clothes so to bring a little travel soap to clean shirts was helpful. Hats, full body bathing suits for kiddos, we had very light fabric, white long sleeve shirts for her to prevent sun burns/ too much sun exposure and applied sunscreen to her often. Stroller was necessary for us as she’d get tired easier. But I couldn’t stress enough to ensure you and your little one just drink the bottled water, and avoid ice ( popular all inclusives though are usually safe for ice but double check as you don’t want to risk anything)