Xenoblade Chronicles 2's upcoming Torna ~The Golden Country DLC will arrive after an update on 13 September 2018 bringing scaling difficulty changes. By scaling, we don't mean automatically updated, but literal sliders for difficulty.
Torna - The Golden City DLC was announced during E3 2018 as a story DLC telling the tale of a group of legendary warriors that go through the tragic history of a doomed kingdom. This sequence of events also apparently drove a hero to go "down a dark path" some five centuries before the events of Xenoblade Chronicles 2 occurred. Players will have to defend themselves from Malos and his forces comprised of artificial lifeforms named Blades and their masters, the Drivers, so they never threaten another PC with an update again.
Anyway, what Nintendo and Monolith Soft didn't announce back at E3 was the difficulty slider feature that will be introduced in the upcoming update and it will seemingly precede Torna -The Golden City by a week. These sliders, seen on the picture below, will let players customise their playthrough's behaviour from anywhere between a stroll in the park and Dark Souls' abusive step-father.
The game currently has two difficulty modes - easy and normal. A third difficulty level was previously announced along with challenge battle mode and the already mentioned story content. The official English name for this mode will be "Bringer of Chaos", but according to data miners, this mode will not have the difficulty sliders maxed out. Therefore, players will be able to customise their experience to be fully masochistic, wrapped up in anime art style.
These sliders will offer some regular difficulty changes such as enemy attack power and frequency, as well as their health and debuff durations. The sliders will also provide players with the ability to customise their party's power by turning down party gauge gains or cranking them up, or doing the same with the player's character.
Some fans are hoping this slider adjustment will be a new game+ option but nothing is officially confirmed at the moment.