6 year old's control issues

Hi everyone, our 6-year-old is becoming more of a challenge on needing control, and I wonder if others have experienced the same and have thoughts or advice on how they handled it. While it's normal for kids to want more control over their lives at this age, she will negotiate control over even the simplest tasks multiple times a day seemingly every day, and throws fits when she doesn't get it. We recognize that she may be following behavior we model (and we are working on that), and we are trying to find ways to give her greater control (pre-tantrum) because we know it's tough not to have that. But we could use some more tools on how to better manage this if others have had success. Or if anyone has a referral they can send our way, that would be great too. Many thanks!