I carry a small bag with rain ponchos for the party( all adults). Back up battery, charge cable for watch and phone. Wallets for the party. Chapstick, hand sanitiser( every place I tried to use Disney’s they were out, Sept 13-17), extra mask filters, sunglasses for party and collapsible tumblers(hydaway) for the party.
I fit all this into a small bag, this past trip used a
castaway club bag and had plenty of space for any purchases made while in the parks.
Do not count on Disney hand sanitiser. On our second EPCOT day a CM actually told us they are only refilling the stations once a day.
The Hydaway collapsible tumbler is great because you can fill it from the ice water stations drink what you want then have it go back to the small size for easy carry. It comes with a silicone straw, lid, neoprene cover and 16oz silicone collapsible cup. Best money spent as I use all the time even when not in Disney.