NPN-transistor to switch 3.3V
Personally, I would use a MOSFET in this application since you are only using it as a switch and you want to keep the voltage drop across the device (MOSFET) as low as possible. Whether or not to use a pull-down resistor on the gate will depend on what device you are using to drive the MOSFET. If you build the circuit, and the MOSFET won’t turn off or acts erratically, use a pull-down resistor.

Here is a great MOSFET tutorial video for beginners. The MOSFET used in the video (Fairchild FQP30N06L) is very common and is one of the MOSFETs that I use the most for Arduino and Raspberry Pi output circuits where I have to control larger devices. (I buy them in bulk!) Pay attention to the part of the video where he mentions “logic level” MOSFETs. That’s what you want to use. The FQP30N06L is a logic level device.

https://youtu.be/GrvvkYTW_0k

Good Luck!