How to pass a lambda expression and call all maximums?

Question

C++ / C#

Can you please tell me how to pass a lambda expression as a parameter to a method and get the result?
For example:
var list = new List{...};
list.Max(15, person => person.Age) // takes T and returns an int
should return the 15% of users with the highest age in descending order.

Answer 1

takes T and returns an int

Func<int, T>

should return the 15% of users with the highest age in descending order.

It's not at all clear what your question refers to.