Yes, the GPT-3.5 model has been fine-tuned using RLHF, this is the text-davinci-003 you can use through OpenAI's API's.
Not sure if ChatGPT has some additional fine-tunings as you can get similar response using text-davinci-003, with the Chat prompt, and a temperature setting between 0.3 and 0.7.
Not sure if ChatGPT has some additional fine-tunings as you can get similar response using text-davinci-003, with the Chat prompt, and a temperature setting between 0.3 and 0.7.