As far as I know there is not integration completed yet for the Tuya Smart Plug (Smart Life App) branded plugs. If you want to have a cloud integration you may need to write your own code, otherwise IFTTT integration is probably the best choice for ya
For ITEAD SONOFF I think you have 2 possible solutions, one involves some flashing and program writing, the other is IFTTT.
For TP-Link you can just search TP-Link Device integration and there is already tutorial on that here.
I suggest you read the SmartThings Development Guide. I was in the same boat and I decided that I need to learn some Java first before I attempt anything. For now i’m just using IFTTT integration to get by (slight delay obviously)