A.H.
HI K. R
I understand how you feel. I'd decided my daughters 3rd year was when she connected to her personal will. When they discover there own wants, and then have fun testing you with them. I'd decided I didn't want her to just do what shes told as an adult and was willing to put extra energy into negotiations from the start. I when I'd ask her to do something, and she wanted something else, I'd think about it. Not every time, but a bunch of the time it was just a silly power trip. And I'd say something like I've thought about x and I changed my mind, you can xx. And then we'll do what I had asked in the first place. I think it's a natural development of there person. I also thought about her sign, my best friend is also an aries, and very strong willed. The harder you push for x the more stubborn they become. So I changed the way I thought about the situation. And found letting her have some control in her life made all the difference for better behavior.
As for time outs when they stopped working I would take some privilege away. Her doll would get a time out, or a tv show she might get would be taken away. That got her attention since she doesn't get to watch much tv, it was a real treat.
I do the same with picking up, if she wouldn't help the toy was mine for a few days. Or the next time she asked for it I'd remind her why it was mine that day. And we'd talk about why.
Anyway that might not work for everyone. So good luck! A. H