son gets jealous of other children

Moms, I could really use some advice or insights from those who may have been through a similar situation. My son, who is now 3 and a half years old, has been showing signs of jealousy towards his newborn sister, who is just 3 months old. Whenever I'm caring for or spending time with his little sister, he often acts out or seeks extra attention from me. It's been challenging to manage his feelings of jealousy while also ensuring that both of my children feel loved and valued. Moreover, I've noticed that he also gets jealous when I hold or communicate with other people's kids. It seems like he feels threatened whenever I interact with other children, and I'm not sure how to address this behavior in a sensitive and supportive way. I want to help my son navigate these emotions and understand that it's normal to feel jealous sometimes, but I also want to encourage positive interactions and foster a loving sibling relationship between him and his sister. Is it possible?