So, my question is that, ls it possible to use a buck converter connected to 5v pin of Arduino as input and set to 3.3v as output voltage of buck converter to power NRF24L01 module
What is powering the 5v on your Arduino?
I don't see that line written anywhere maybe you should go and read again.
Isn't that why @bluejets asked the question ?...R
Also I had a question that will it be safe to connect it directly to 5v pin because the module datasheet shows that it requires 3.3v.