I don't think a situation where your kid is ' loosing ' and you ' winning ' would improve things. I don't believe that we can break kids into submission , they will resist even more. Even behaviorists , and I am not , say that honey catches more flies than vinegar so use positive reinforcements. personally I prefer workingwith -problem solving approaches like that of the explosive child , not a doing to approach.
I think the starting point has to be - relaxing the environment , putting behaviors into basket c = ignoring in the time being and trying to bond , connect in one and one time , using dialog questions to direct conversation , you listen , she speaks. Try to focus on perspective taking, empathy , addressing concerns - what's the problem first and then look at solutions. It is easier to talk about non emotive issues first , stories , new s items, your experiences , video story etc what she thinks, what the kid in the story thinks , how could they solve the problem. Avoid saying NO , we set limits also when we reach mutually satisfying agreements. This is not a quick fix , it is a process ,but helps the relationships and promotes various cognitive skills that may be lacking. I recommend getting the latest edition of the book , the explosive child and trying to find out what is getting in your child's way. Greene says kids do well if they can , not kids do well if they want to. Defiance can be explained as pure choice or a learning disability in areas for eg frustration tolerance , flexibility and adaptability
I hope this helps