gpt-5* reasoning models do not have an adjustable temperature parameter. It seems like we may have a different understanding of these models.

And, like the other commenter said, the temperature may change the distribution of the next token, but the reasoning tends to reel those things in, which is why reasoning models are notoriously poor at creative writing.

You are free to run these experiments for yourself. Perhaps, with your deeper understanding, you'll shed new light on this behavior.