These two meet in a boss area. The center is clear, but there's also trees, rocks, and tall grass around it so stealth is an option if they so choose to use it. They're both fully leveled with all their gear and powers. They have all the abilities they can get from their games.
Who wins? I honestly think it's a little hard to tell. Sekiro obviously has the supernatural thing going for him so that's an advantage, but Jin is not exactly "realistic" himself, despite his story not featuring any fantastical elements (and actual Oni and the likes do exist in his world). Meanwhile, Jin vastly outpaces Sekiro in terms of gadgets and tricks he's got. Still, Jin's gotta kill him atleast twice for it to stick.
Or, if you want to make the question a little more interesting, who would you rather play as and who would you like to play against?
