Here's the syllabus for the Cambridge Critical Thinking AS & A level

https://www.cambridgeinternational.org/Images/597412-2023-2025-syllabus.pdf

They used to offer it as an end of GCSEs subject in grammar schools in the UK when i were younger (Maybe they still do, i don't know). My Ex took it.

I (a pleb) went to a plebs school though so didn't get the opportunity