(Lee, 17/10/2019)
Short answer: classical guitar range is 3.5 – 4.2mm. Flamenco guitar range is 2.8 – 3.5mm. I am sure you could find the odd exception. As the action increases, you can get more volume without buzzing. On the other hand it is (obviously) harder to play and it also starts to cause intonation issues.
hope this helps,
Yrs, Nicholas Mahoney