I would say it depends on where you are, and what schools you are targeting, and what school she is currently in.
Say you were in the really competitive area, with lots of preps and your kid is in state....
Or she is in a non-selective prep that isn’t the ‘top feeder’ - then it’s one situation.
Or you are in a more relaxed place where everybody is in the same sort if schools and some later decide to sit 11+....
Also - obviously - things depend on what sort of child your Dd is.
I am in a quite competitive central London area. So - my approach was always to do a little bit extra with my kid over time - so that when 11+ came around she’d need polishing of her skills rather than lots of hard pushing.
So - in Y3-4 - yes - it’s making sure she was reading, as well as being exposed to a variety of books - fiction and non-fiction.
In those years she kept a reading journal over the holidays. As well as sometimes writing a regular journal as well.
There is also general development and exposing them to interesting topics and events - whether cultural, political or scientific. Not as possible in lockdown - but at the same time all of the resources - galleries and theatres and lectures can be found online.
And finally - math. Have always made sure we keep it up spring holiday to solidify and cover a bit more advanced concepts. This way - they always could hit the ground running in Sept after holidays and always felt comfortable with math throughout years, even as it got progressively difficult.
Interestingly - thinking back - I haven’t been doing ‘enriching’ things with my child solely for the purposes of exams. I’d have been doing similar things regardless as to me it’s something I seemed to enjoy doing and I thought it’d benefit their development