It depends on the type of argument. A shouting match is wildly different from people insulting and disrespecting each other passive aggressively. And what do you want to achieve with the diffusion? Do you want to avoid immediate escalation into violence, or do you want people to come to some sort of agreement?
In either case, people tend to argue because they both feel attacked. Making them feel heard, and then explaining that it does not help to argue with the other party, because they don't want to listen (right now), would be what I would try.
Ps. Random tip: you can edit titles in lemmy. For example, you can change "apart off" to "a part of".