Use emotional vocabulary. Naming the feelings helps children to be able to identify them for themselves later on.
Modelling positive interactions. Children absorb all the conversations they are part of and the ones they overhear! If they hear things that make them worried you might have to take a bit of time to explain how the other people were feeling and why they reacted as they did.
Use humour and be lighthearted where you can; that really helps to de escalate things. That doesn’t mean you are condoning behaviour! It means you are in charge of managing it.