My ragdoll turns one year old tomorrow.
He won't ruin the floor or pee on things (at least once he has the litter box figured out), but he'll definitely eat wires and chew on stuff. You can prevent this by coating them in lemon juice, and getting chargers for things that have braided cords, like this.
Start with him in just one room rather than giving him freedom to roam the house, so he gets used to that for a couple of days. Also minimizes the likelihood of him peeing on things before he figures out where the litter box is.
Get him a couple of different types of scratching posts, carboard and carpet and hemp and see what he goes for. Unfortunately, this does not stop them from scratching other things. You can use double sided tape for that if you're really worried about it, but you can't really do that to the stairs.
Also make sure there are elevated places for him to go, which might be a cat tree. He will want to be up high.
Get a variety of toys and see what he likes to play with. Pretty much all cats like wand toys.
Mess around with his paws, ears and mouth as much as possible early on so he gets used to it. If it's a rag doll, this is easier.
Get good cat food. Origen is pretty good.