A warlord is typically a leader and not a job title
Their "job" is not so much a job as it is simply a position of leadership which they have demanded and which others have willingly allowed them to take
As a leader a warlord will do as they please, typically inventing the role they wish to partake of in the government and delegating any other tasks to subordinates
For a more specific answer you would need to identify which warlords you are talking about, what part of the world you want to know about and from what time period. Warlords throughout history have had a variety of behaviors, most of which are variations on being a general in a time of war and or taking over as a dictator in combative nations
She assinated the warlords with a gang of rebels.
Warlords of Utopia was created in 2004.
Warlords of Atlantis was created in 1978.
Robot Warlords happened in 2000.
Warlords Battlecry was created in 1999.
Warlords Battlecry happened in 1999.
Winged Warlords happened in 1983.
Winged Warlords was created in 1983.
The Warlords was created on 2007-12-12.
The Production Budget for The Warlords was $40,000,000.
Warlords of Utopia has 192 pages.
The duration of Warlords of Atlantis is 1.6 hours.