Certainly. There will be meta progression in the form of character stories and permanent loot from each run In between runs you'll return to the alternate version of Elden Ring's Roundtable Hold ...

Elden Ring Nightreign adds a new twist to the classic Souls-like bloodstain mechanic. Instead of simply showing how a player died, bloodstains now let players loot items from a fallen player's ...

Based on what little information is currently available, Elden Ring Nightreign seems to be looping in disparate mechanics from other soulslikes.