I think, for the vast majority, the pressure comes from the schools, the press and being so visible via social media etc, not the parents.
I have not seen one parent be anything other than supportive, making sure their dc know that, no matter how they do, they will be loved and supported through the next stage and there is always a way forward. It’s the schools that keep telling them that anything less than top grades at GCSE will mess up their whole future. Honestly the amount of pressure the school put my dd’s cohort through was appalling, it just made the whole thing harder for them. How on earth can they do their best work whilst struggling with severe anxiety in case they fail?
Our family sees things slightly differently, as several of us have taken different routes to their qualifications/careers, due to illness/disability. Unfortunately, even knowing that dd was still affected by the constant pressure from the school.
I wouldn’t mind so much if it felt like it was misguided, but coming from a place of wanting the best for their pupils. Sadly for a lot of schools it’s more about league tables and published results.