Why is the digitalWrite output low in voltage?

Other Hardware General Electronics
11

I initially was using Relay: SRD-05VDC-SL-C (How to Set Up a 5V Relay on the Arduino | Circuit Basics)

then I tried also using Mosfet IRF 1405 (IRF1405 Datasheet)
Gate threshold is 2V-4V.

Thank you so much for your assistance.

I wonder if it is too much load on Arduino to have a temperature sensor, and then the LCD display. if I need to have the pin to have a High +5V?