Spend enough time in Skyrim (enough time being a few minutes) and you'll probably wind up becoming annoyed with an NPC. Maybe it's an offhand comment from a rude guard, maybe it's a shopkeep whose prices are too high, or maybe you just don't like the way someone looked at you. Whatever the reason, you might find yourself itching for a fight. And, while you're obviously a bit touchy, you're also honorable (I'm guessing), and you'd like that fight to be a fair one.
Draw—A Dueling Mod, for Skyrim Special Edition (and original-flavor Skyrim as well), lets you challenge NPCs (any NPC you like, in fact, even essential ones) to a duel via a new magic shout. There is the requirement that the NPC has to have a negative relationship with you (your followers, for instance, won't duel you), but I think you'll find that screeching angry magic words into some stranger's face about how much you want to fight them will probably lower their disposition a bit. Then, it's go time.
What's the difference between challenging someone to a duel and just attacking them? Well, the duel is a respected ritual of combat, so unlike when you just start randomly stabbin' some dude in the middle Whiterun, no one else—not guards, faction members, or witnesses—will interfere with your brawl. It's one-on-one (unless you want to cheat and have your followers join, which you can elect to).
Perhaps better still, you don't have to fight to the death. You can—once your dueling partner drops below 20% health, they'll fall unconscious, at which point you can kill them if you like (again, this goes for essential NPCs). Also, there's the chance of accidental death, both for you and your opponent. Typically, though, the duel will end with either you or the other fighter being knocked out but not killed.
Plus, if you want to fight with fists rather than weapons, just don't draw a weapon and your opponent won't either—unless they're losing and panic, which is a possibility. You might, from time to time, find a boxing match has turned into something a bit more dangerous if your dueling partner suddenly takes out a sword or an axe. Another possibility: the losing party may decide they've had enough and flee.
Draw is available here at Nexus Mods. What are you waiting for? I know there's someone in Skyrim you'd just love to (honorably!) pummel into the ground.