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I use the Yongnuo YN-622C triggers for the Canon flash system. It allows remote Speedlites to function under radio triggering just as they would using the Canon Wireless system of optical triggering.
Under both systems, ETTL allows 3 Groups of Speedlites to be used off camera, so one could have, for example, a key light or lights on Group A, fill light(s) on Group B, and hair light(s) on Group C.
You'd set the ratio of key:fill + hair (Group C is a little different than A and B in how it is metered), and the camera would fire preflashes to measure and set the absolute output needed to achieve "proper" exposure within those ratios.
You can also set them for Manual power levels, and set each Group's power level independently.
The YN-622C requires newer Canon cameras that have flash control menus, because the radios have limited controls on the units themselves.
Non-TTL triggers will fire the lights from the camera, but the camera won't control the power levels; you'd do that manually, either at the lights or remotely depending on the system.