This is my house and my kids are 8 and 5
They are both strong willed. “Sounds like you both want to help me make fish, awesome!” Then give them both VERY special jobs to do. “Oh it sounds like you are both very hungry, how can we fix that”.
I think they mostly just want to be heard and to be validated. They have no clue what “being nice” and all that means. They are very much egocentric at this stage.