Hriston
Dungeon Master of Middle-earth (He/him)
Social Interaction rules are in the DMG, starting on p 244. They suggest a DC 20 Charisma check to get hostile creatures to cooperate as long as they aren't taking a risk or sacrificing anything by doing so.From the game that I'm in, rules for how to run Intimidation. Our Paladin tried to get some bandits to stand down since they would likely end up slaughtered for no reason and we had to take some time to figure out what DCs should be and what those effects would be.
In the end, the GM made the paladin make an Intimidation check against the bandit's Wisdom Save mod +10. He gave advantage on a later check when the bandits started getting slaughtered. It worked, but this was a new GM who had to really think about how to handle the mechanics when this could have been a simple check that kept the momentum of the scene going.
Your DM might also want to check out the rules for Morale on p 273, which is a DC 10 Wisdom save under certain circumstances and helps the DM decide when NPCs give up fighting and flee or surrender.