What logic is implemented inside the task/thread?

Question

C++ / C#

Task task = new Task(() =>
{
    
});

As far as I understand, this is called a "thread pool", in which we can control the logic of the thread, how it should behave, etc (correct me if I'm wrong). But I didn’t find the implementation itself, or an example, on the Internet (well, or I found it, but with a too complicated implementation). Can you provide an example of using a thread pool? What logic is written inside?
PS - do not throw an example of a metanit, except for obtaining information about the stream, there are no other ways to implement it.

Answer 1

For example reading a large text file.

Answer 2

From management there is CancellationToken, if suddenly you were asked to stop from outside.