Depending on your high school, you may also have the option of your son transferring to a different HS counselor. At our public HS, one of the GC’s was excellent in getting to know kids’ interests, chatting with them during lunch periods, etc. and wrote amazing letters for the kids who were at the top of the class. Another was, shall we say, better suited to help the kids who were heartbroken because of a breakup, or because so-and-so looked at her funny, before sitting at another table. Another was the assistant football coach who seemed to be only concerned about kids remaining eligible to play the rest of the semester. But kids got assigned to their GC based on alphabetic order. A concerned parent generally is not seen as overbearing or pushy if they want to advocate for their child, and to request a GC that is a better match for their snowflake.
There are schools that have one GC for 20 kids, while other schools may have several hundred kids per GC. The student is not faulted by colleges for things they cannot control. And for the most part, GC’s are generally willing to accommodate parental requests, to the extent possible, as they share the same goal of getting the best possible outcome for the child - they appreciate the help.
There are a number of threads about GC’s here at CC, with a lot of good advice, but they are not one-size-fits-all.
In your situation, OP, I would expect your amazing S will be a dream for the GC, even if she does not know him well. Having a concerned parent and a motivated, high achieving student, likely means your S has his act together, and has a great shot at getting accepted at multiple highly selective/elite schools. Your S will be organized and she won’t have to hound him for different missing information, or to explain what a good score on the SAT tests means, etc. There are undoubtedly scores of other kids who are not as easy to help - who may require a lot more guidance.
At the same time, it can be very frustrating as a parent to have to deal with a GC. I suggest you make an appointment with her well before the school year ends, to have a discussion about goals, etc, and to help set expectations. Some GC’s work over the summer months, others do not. Once you know the usual routine at your school, see what if anything might need to be different for your exceptional child, and then ask how you can help. Chances are, you can learn answers to any of your questions here, but meeting with her soon allows you the option to think about things over the summer. If your S writes his essays over the summer, or at least gets his list together, he will continue to be ahead of the game compared to the majority of other students. If the GC doesn’t have to help him pick a list of potential schools, she will be grateful for your assistance, and please stress how much you understand that you are working toward the same goal.
Best of luck.