Does anyone know where I can find a step model or a drawing of the relay board module? Thanks
You can export STL/STEP/other from the boards using KiCAD…on the product page we have the .brd and .sch files https://cdn.sparkfun.com/assets/5/1/1/1/e/Qwiic_Single_Relay.zip that you import into KiCAD, then simply export them back out 
For rough sizing here’s a handy diagram
