I would how they engage pupils who have not previously fully engaged.
There can be a big difference between state and private or between different schools generally). . At a good school kids may be used to putting themselves forward and trying things out. They will be used to trying out for the play or the sports team and perhaps not being selected, but trying again. They may be used to voluntarily sitting the maths challenge in their lunch time, or staying late after school.
Some schools simply make the provision and leave it for the kids to engage meaning that the quieter ones get neglected. (It is a criticism I have heard about Eton!) Others are more nurturing. DD noted in Yr 7 that some of her friends who came from state primaries were aghast at being asked to stay late for after school stuff and simply refused. To her, coming from a prep, it was obvious. Being selecting for a school team was an honour and a duty so you did it.
To make the most of a "cool to be clever" culture, a child needs to take part in teams, choirs, societies, debates, MUN or whatever. This might prove quite a switch at Yr9, but a really useful skill to have before starting University. What do the school do to encourage those not used to putting themselves forward.