Thanks @DjDemonD , @alkis as simon has mentioned you can control relays from a number of the outputs including fans and heaters. If you are using one as a fan control then the simplest option would be to use one of the FAN outputs if you are not already using them all for something else. You need to use bang bang control on a heater - for the fan set it to either full off (0) or fully on (1) and you will need to prevent the sicer from trying to set the fan to an intermediate setting.
I can't confirm if that specific relay module will be OK being controlled by 12V or 24V as there is no data sheet on the listing and the JQC-3F(T73) relay datasheet is very limited, however the main issue is its a 5V relay. you might be able to get away with a series resistor to limit the current. alternatively you could use a 12V or 24V relay depending on what system voltage you are using. The final option is to use one of the spare IO pins on the expansion header (at 3.3V) and use a fet to convert that signal to 5V for driving the relay.