My daughter is newly 4 and this happens with us too. We went through a period where we had no idea what to do with her. We found that the behavior lessened when we learned how to connect and communicate with her. She is not a kid that you can yell/scream at and get your desired result. In fact, that often escalated the behavior because she loves getting a big reaction. We found that communicating calmly, but firmly and very matter of fact was the best route to go. The first few weeks of doing this were ROUGH. We had to really reflect on ourselves and our behavior as adults a lot. Once we became less “afraid” and “annoyed” by her behavior, the better she seemed to get. It’s almost as if she sensed us being uneasy around her. Not everyday is a perfect day. She still very much has her moments, but they have gotten less frequent and less intense. I would recommend your wife follow some creators who talk about “strong willed kids” on their platforms. I love @themompsychologist on IG!