+1 to this.
I've posted this elsewhere on the forums that there should be some method of ending combat besides the death of all your enemies. You can technically knock them out, sure, but since they remain hostile this basically just delayed the murdering. Also it can be very tedious to do this.
My suggestion is similar to yours: a persuasion or intimidate check, with the DC decreasing depending on how many enemies you've incapacitated.
-the DC is somehow related to the CR of the enemies: E.g., DC 15 for the tieflings guarding Sazza and DC ~25 for combat with the goblin leaders
-kill/incapacitate their leader (Minthara, Zevlor, Kagha): DC drops by ~5
-every enemy killed decreases the DC for intimidation check by 2 and the persuasion check by 1
-every enemy knocked out decreases the DC for persuasion check by 2 and the intimidation check by 1
-to prevent spamming this check to cheese every combat, maybe you can only make this check once or twice per combat and it costs an action to do
This would have many benefits
-A quick end to tedious fights that you're ~guaranteed to win, but it will take many more turns to actually kill/knock out the remaining enemies.
-Possible interrogation of enemy leaders instead of just killing them
-Enabling additional roleplay: e.g., playing a PC who is against killing
-A middleground between no combat and death. Again, why should I be forced to kill those tieflings guarding Sazza? I should be able to intimidate them: "Hey, I'm much more powerful than you and if you continue fighting me you'll die. Surrender." Knocking them out is BG3's current option for this, but unless things have changed, they remain hostile and leaving them alive can possibly lead to the entire tiefling camp becoming hostile.
