These aren't "unlocked" through gameplay—they are available immediately at the character selection screen once you own the Eternal Collection.

Following the defeat of Diablo in the base game, the expansion introduces a new threat: , the formerly revered Archangel of Wisdom who has returned as the Angel of Death .

: Specifically from the Necromancer DLC, you get 2 additional character slots and 2 extra stash tabs . Top Deep Features Diablo® III Eternal Collection - Battle.net

: Unlocks the Necromancer class, two additional character slots, and two stash tabs. How to Unlock DLC Content

The Eternal Collection includes three main components that would otherwise be separate DLCs:

The Eternal Collection is essentially a "three-in-one" bundle that includes: Diablo III Base Game

The Eternal Collection is a bundle that includes the base game, Diablo III, and its expansion, Reaper of Souls. The DLCs (or "content packs") available for the Eternal Collection are:

I notice you’re asking about for Diablo III: Eternal Collection , specifically using terms like “DLC unlock top” which often refer to cracks, pirated DLC unlockers, or unauthorized key generators .