This module has a multi-turn trimpot (potentiometer) that you can use to adjust the output voltage. Since the trimpot has 25 turns of adjustment you can easily adjust the output of the module to exactly the voltage you need.
Boost converters are a great way to easily increase a given voltage, but that boost comes at the cost of less output current compared to input current.
Since this is a boost converter the output voltage has to be higher than the supplied input voltage.
If you need to decrease (step-down) a voltage consider using a buck converter such as our LM2596 buck converter module.