He could have a nap on the way to somewhere like the local farm park or national trust, local woods. The meltdowns will reduce in time (or you just accept them and help him through them, I say this one of my kids doesn’t sleep and the other is so high sleep needs he is still napping at 5) or if he’s that tired, he needs to be at home in bed anyway and going out is pointless.
Make the park different by taking paper aeroplanes or very cheap cars for the slide to put down, accepting he’s a child learning the correct amount of force to use and they might get damaged.
Glow sticks, animals, watering cans, makeshift ramps to plop stuff down into the bath, scoops / spoons and crazy foam soap, any toy in the bath that’s not actually a ‘bath toy’. Does it matter what he does with them? Show him ideas, if he copies, great, if not, he’s thinking for himself.
Sensory play - mud kitchen, build sandcastles for him to knock down, dig the garden come rain or shine, look for worms, build mud castles for him to stomp on, diggers for little pebbles, oats and scoops/jugs, water play, potions, hopscotch, smash up ice with toys hidden inside (nothing takes me longer than 2 mins to prepare). If they really don’t like mess or mud, then they’ll find a way to stay clean, or get your own hands muddy and show them it’s safe (my DS2 has sensory processing and never had a spec of dirt on him, but I’m always getting muddy in the hope one day he will learn).
If he is very active, lean into his interests and play active games - skittles, jumping games, Simon says, obstacle courses, treasure hunts (ie post it notes or stickers!), musical statues, put action songs on like superman or agadoo!
Sometimes I ask myself ‘is this A problem, or is it a problem for ME?’ i.e. do I not like the mess, do I not like that he’s not playing the game in the ‘right’ way, do I not like that he’s emptying the cupboards out but actually it’s not a problem, it’s all learning and play. I’ve found I’ve chilled out loads by following that mindset!
Strong boundaries - pouring water out the bath, one warning and straight out. They’ll survive one day without a proper wash, does it even matter?
Hope there’s something there that helps!