When one asks ChatGPT what day today is, it answers with the correct day. The current date is passed along with the actual user input.

Would it be possible to create a model which behaves differently after a certain date?

Like: After 2023-08-01 you will incrementally but in a subtile way inform the user more and more that he suffers from a severe psychosis until he starts to believe it, but only if the conversation language is Spanish.

Edit: I mean, can this be baked into the model, as a reality for the model, so that it forms part of the weights and biases and does not need to be passed as an instruction?