Non-Electrical-Engineer-Here: Can I use a 5v 2A power supply with any 3.3V regulator?
Find out how much current your NRF24I01+ needs and get a regulator that can provide at least that much current. Also, get a low dropout regulator that can operate with a 5V input and provide the 3.3V output. After having chosen a regulator, determine how much power it will dissipate and provide adequate heat sinking.