How does the Leader title work?

[Zakrya]

recently, I noticed that we issues the title of the head of state is always mentioned as simply "leader", by chance the title of the head of state of a nation is always defined by nationstates as "leader" or the player can define the title of his head of state any way you want?

[Dawn Denac]

As Luna says here, you'll receive an issue to change your leader's name at a certain population threshold.

[Imperial Fiji]

It’s so that it can be kept simple, you don’t want to call the players leader a king if their a president, you don’t want to call them a her if their a him, stuff like that.