Yes. In Palworld v1.0.3, Necromus can get Lord of the Underworld through currently verified methods: it is a fixed passive. Lord of the Underworld is a fixed passive on Necromus in v1.0.3; every Necromus has it. The facts behind this answer are graded B and come from 2 registered sources.
Reason
Element Boost Dark +30%
Rank
3
Random pool
No
Other Pals
2
Necromus breeding recipes
1
Fixed passives on Necromus
2
Custom slots available
2
Verified evidence claims behind this verdict
2
Necromus parent pairs with a direct source of Lord of the Underworld
1 of 1
Lord of the Underworld breeding route for Necromus: 1 of 1 parent pair include a direct source (Necromus).
Why
Lord of the Underworld is a fixed passive on Necromus in v1.0.3; every Necromus has it.
How Lord of the Underworld can be acquired on Necromus in v1.0.3
Current method
Available for Necromus?
Note
Fixed / innate
Yes
Lord of the Underworld is fixed on Necromus — it is born with it.
Random pool (catch or hatch)
No
Lord of the Underworld: no verified rule puts it in the random pool for Necromus.
Implant (Surgery Table)
No
Lord of the Underworld: no verified item method grants it here.
Breeding inheritance
Yes
Necromus can inherit Lord of the Underworld along a verified breeding chain, under the standard passive-inheritance rule this dataset has not independently sourced.
Verdict per requested component on Necromus in Palworld v1.0.3
Lord of the Underworld is a fixed passive on Necromus in v1.0.3; every Necromus has it.
B B · 2 sources
How it reaches this Pal
Lord of the Underworld is fixed on Necromus — it is born with it.
Every Necromus in v1.0.3 is born with Lord of the Underworld, so none of its 1 breeding recipe has to carry it.
What you can do now
Lord of the Underworld is fixed on Necromus — it is born with it.
Alternative: Necromus can inherit Lord of the Underworld along a verified breeding chain, under the standard passive-inheritance rule this dataset has not independently sourced.