I've said it before but everything I see of Olise in the World Cup confirms me in the view that he is the most gifted footballer to play for Palace. Not the most important, or my favourite, but simply the most gifted.
What is noticeable is that everything he now does, he was doing from the very start. He hasn't changed particularly. He always had that astonishing first touch and awareness. He always had that ability to carry the ball at speed but, at the same time, to have his head up and see a pass, and then the ability to play it with perfect timing and weight whilst he is still on the move. Every through ball is played with no alteration or deviation in his stride pattern, and goes exactly where it should, when it should. He is preternaturally gifted, and it showed from the outset.
Olise wasn't especially showy. He rarely dribbled past three opponents or did something incredibly eye-catching or domineering as an individual. What he did was do all the key things to an incredibly high level every time he did them. What changed over time was how often he did them.
As to what role Palace played in his development, well, I think a big part of it was that over time he got stronger physically as he got older and worked on it, but he also got tougher by going up against tough opponents every week, rather than playing an hour here and there, as he would have done if he'd signed for a big club too early. He also recovered from some bad injuries whilst here, and came back to find that he was still first choice; The club hadn't replaced him with an expensive signing immediately, as would have happened at a big club.
Mostly though, he just applied his skill set again and again until, incrementally, he went from decorating games to deciding them. There was no big penny-drop or sliding-doors moment. All that was necessary for him to become world-class was to sign for a top-flight club where he would always be first choice, even if was inconsistent or quiet for spells.
It would be nice to think Palace made him, but in truth he could have signed for any one of about eight mid-table clubs and end result would have been the same.