For comfortable commuting on mixed but mostly paved surfaces 32 mm should be enough ... I wouldn't go that wide.

No bike (except maybe a fat bike) can handle full-on sand. but if there is sand across a paved path a narrower tire can cut through to get to the pavement. As rekmeyata says, just don't try any sudden moves ... smooth and steady, turn in gentle arcs, and just ride.

As an aside ... there is quite a debate going on about overspecialized bikes, and how every riding style has been pigeon-holed.

I say, some riders are pigeon-brained.

Three of my road bikes have 23-mm tires and I would not hesitate to take them anywhere .... well, not eh CF ... but the metal bikes, why not? They are metal ... they are bikes? I wouldn't bomb down steep downhills and bash through rock gardens, but I would and have ridden footpaths through the woods. Granted, a bike designed for specific terrain will work best on that terrain, but ... I mean, would you drive a car across a field?

If the bike path is paved but has occasional blows of sand (mini-dunes) they won't be packed, so treat them with care, but they won't be deep ... slightly wider tires won't make that much of a difference. I commuted for years on 25s and 28s without an issue ... I never worried about tire width, so long as the bike worked I rode it wherever I needed to go.

Main thing for a commuter, IMO, is rack mounts. A lot of people will also say fender mounts, but I always went for a full clothing change at work anyway. But definitely rack mounts ... because I hated riding wearing a knapsack. Some don't mind.