To help understand the MOSFET's operation, here's the LTspice sim of a simple circuit to control the load's current with a MOSFET close to the IRLZ44N's characteristics (with a Vgs nominal threshold of 1.9V):

Note that the MOSFET goes from full OFF to full ON over a Vgs range of about 0.2V from 1.9V to 2.1V.

The MOSFET dissipated power (red trace) goes from zero to 3W maximum, where the voltage across the transistor equals the voltage across the load, and then goes down to near zero again when the transistor is fully on.

To help understand the MOSFET's operation, here's the LTspice sim of a simple circuit to control the load's current with a MOSFET close to the IRLZ44N's characteristics (with a Vgs nominal threshold of 1.9V):

Note that the MOSFET goes from full OFF to full ON over a Vgs range of about 0.2V from 1.9V to 2.1V.

The MOSFET dissipated power (red trace) goes from zero to 3W maximum, where the voltage across the transistor equals the voltage across the load (as per the Maximum Power Theorem), and then goes down to near zero again when the transistor is fully on.