This forum is for people who are using the Samsung SmartThings I Home Automation platform. Consequently all questions and answers will be in the context of that platform.
While there is a way to use the sonoff ifan02 with SmartThings, it is very technical and the setup is quite complex. See the following thread for discussion.
There are much easier methods with devices that can be integrated more smoothly with SmartThings. See the community FAQ on fans and lights… (although the thread title mentions ALEXA, it applies to any fan/light SmartThings set up.)
FAQ: 2020 Ceiling Fan and Dimmer light wall mount control compatible with SmartThings and Alexa?