Firmware details below. I'll get a picture of the board soon.

Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
Firmware Electronics: Duet WiFi 1.02 or later
Firmware Version: 2.05.1 (2020-02-09b1)
WiFi Server Version: 1.23
Web Interface Version: 1.22.6

Hello. I have a Modix Big60 V3 which has manual control for the bed heaters (not connected to Duet). I am wondering how I can wire up this IoT relay below (basically which pins and what GCODE command I should be using. The goal is to have the heaters turn off after a print. Thank you.

https://www.sparkfun.com/products/14236

The IoT Power Relay is designed to allow you to safely control an outlet device that operates at 3--48VDC or 12--120VAC. Each IoT Power Relay features a single input (from the included C13 power cable) to four outputs: one normally on, one always on, and two normally off. The durable SPDT control relay is rated at 30/40A, for 400,000 operations.