I think that too many things play into academic success at secondary. The child themselves, the parents, the teachers, the school ethos and culture and sadly their friends which are hopefully a positive influence. Top table at primary though is great foundation for secondary.
Ds1 was average and Ds2 excelled at primary and they both came out within the top 5 children in their secondary and that did mean achieving mainly 9s with some 8s but I sent them to a high achieving, incredible progress 8 school with amazing pastoral care.
Their friendship groups were also high achievers who cared about doing well. They kept the same group from year 7 to year 11. Ds2's group were bullied a lot because they were academically able, called names that confirmed this. The school stopped it every time it started (different children each time) and they had the resilience to still do well.
School start right from year 7 with parents in school on an evening with the children showing them how to research for homework, what sites to trust, how many things they should be looking at and what they expect so as parents you know what level your child should be aiming for. After all you are signing their homework diary to say they have done it which should mean you are checking it.
The school report has the usual attitude to learning but also a how well prepared your child is, do they contribute in class, go above and beyond reading around the topic to fully grasp it? That can be as simple as watching films like Elizabeth or Pride and Prejudice to see what society was like because context is relevant for GCSE English Literature.
School also had amazing teachers and would have those personal growth days where they made the children look ahead at different jobs and what they paid, what housing you could get locally if you had those jobs because minimum wage to a 12 year old is a shit load of money whilst you live with your parents but can you only afford to share a house or do you earn enough to have one all to yourself? What car could you buy, how much is a car? What holidays you could have, they all loved researching that in school. They were given pretend jobs and had to search Rightmove for rentals and Tui for holidays, they were given budgets, listed things like council tax and house insurance so they fully grasp all the things that eat your money every month.
This was all to emphasise choices, you do well in your exams from GCSE to A level then every door is open to you, you do poorly then lots of things are no longer available. School wouldn't just give a detention for not doing homework, they would support them doing the homework and ask why it wasn't done, what could they do to help? There was also a homework club every day after school. As I said, an incredible school and the low ability children do really well on Progress 8 too so it isn't all about high ability children.
Both Dh and I went to uni so our children have visited our old unis with us when they were in lower secondary years and we talked about it.
My children went to Warwick and Durham unis.