The question was: How and in what way do you exert your control?
The simplest answer is that control is understood. But, that leaves out all the fun and interesting parts.
A D/s relationship is about consent being understood, a given. After that there are the fine points about how far things will go. But, the consent is a given which means I have the power in my hands. I can use tools, words, bondage, mental bondage, etc to confirm, enforce or enjoy having that power but, one of the best things is using whatever I like to enjoy having that power of consent.
I’m fairly creative. I have fun designing scenarios. I like domestic discipline with spanking, collar, leash and teasing and torment. I like the plan of having a sub in bondage, wearing a blindfold and being subject to my whims. Maybe a lot of sensual touches, maybe tickling, maybe the suspense of being ignored awhile. I like elements of Gor too, with a male submissive who has strict rules for behaviour, how to sit, when to sit, what to wear, etc. I love bringing in all sort of elements from BDSM, and other sources of inspiration. I do know that I am not into messy stuff like diapers, pee or poo play.
Control can be exerted with a whisper, a soft touch or the crack of my hand on a bare ass cheek. Control can be exerted from having a sub perform a spelling bee, having a sub lie in the snow while I pose and photograph him, a strict voice (my ten year old niece calls me a dragon because I control the kids with just my voice and the rare swat on the ass).
So the short answer is that control is assumed, but there is far more to it. I would say that a sub who tried to be too disobedient would not work out for me. I like the sub squirming in bondage but if he were bucking my authority the authority would just be gone and so would I. I won’t put up with a sub who thwarts my authority or acts like this is all a game. There are a few rules but there are rules.