Borderlands 3 World Drops are items that drop from any suitable Loot Source in addition to their dedicated sources.
There are around 150 unique items in the Base Game - World Drop pool, so for farming a specific shield it's best to seek out its dedicated Loot Source.
If you still want to test your luck, you should equip a Shlooter Artifact to increase your chance of a World Drop by 1000%.
Shield - suitable Loot Sources:
- All Enemies:
Bosses, Crew Challenges, Generic Enemies, …
- All kinds of Chests
- Vending Machines
- Slot Machines: Tink's Hijinx or Vault Line
- Diamond Loot Room
⚙️ Recipe for mentioned chances