Even "high-level" Elden Ring veterans will have a tough time in the DLC thanks to unique Sekiro-like difficulty scaling

gamesradar.com:

The new Elden Ring DLC will boast a leveling system similar to that of Sekiro: Shadows Die Twice, so you won't be able to grind your way through Shadow of the Erdtree.

Speaking to Famitsu in a new interview (translated via Reddit), Elden Ring director Hidetaka Miyazaki was asked whether there were any elements unique to the DLC. He said that there are, and pointed to the brand new leveling system in Shadow of the Erdtree, which he compared to the attack power system in Sekiro. 

FromSoftware's 2019 shinobi action game didn't actually have a traditional 'leveling up' system like an RPG, but instead let the player periodically enhance their attack power and health whenever they either collected four special Prayer Beads or managed to beat a powerful story boss.

Miyazaki says a system like this will be present in Elden Ring's Shadow of the Erdtree DLC, but only with regard to the player's attack power. It's basically been designed to make sure players can experience a fresh challenge in the DLC no matter the level they're entering at from the base game, which sounds like an excellent approach for the RPG.

It seems there will also be ways to bolster our DLC attack power outside of the traditional leveling system in Elden Ring, with Miyazaki again presenting exploration as a way to power up for difficult fights. We can only guess as to what this method is right now, but if you were thinking about grinding out levels for your character before Shadow of the Erdtree releases later this year on June 21, you might want to cut those plans short and save your time. 

Miyazaki recently said that Elden Ring wouldn't be the same without Dark Souls 2 , putting the black sheep of FromSoftware's modern game on a lovely pedestal.