If you are dealing with humans, you don't have to do much to create conflict. Trust me, I've held elected office for 12 years, and people will find something to complain about.
When you have stratified society, as in Middle Earth, the people on the bottom will eventually realize that people born into wealth and power are no better than those born into poverty, especially in times of peace when the nobility grow complacent and comfortable in their positions.
Nobles vie for wealth and power and those not capable of generating wealth will seek alternatives to earning wealth and power through conventional means; they will look at intrigue and political maneuvering. Factions will appear and eventually a leader will emerge.
One way for an incompetent noble to gain power and influence is through war. Enemies and threats can be invented as even fair market competition could be painted as a threat.
There is always somebody who believes that could do a better job if they had sufficient power. Things get even more interesting when more than one ambitious person appears to compete for the throne.
When I play in a campaign, I always aim to be king or emperor.
Government is inherently corrupt. Government functionaries constantly seek ways to expand their power and influence, even create crisis to exploit. Given time, all governments become self-serving.
The Roman Empire expanded its borders and conquered provinces in order to provide free bread to the citizens of Rome. Rome eventually collapsed after Romans stopped serving in the Legions so they had to enlist foreign soldiers and commanders.
Corruption and incompetence prompted the government to coin debased currency to the point that Rome would not accept their own coins to pay taxes.
No, you don't have to go very far to find enemies.