EzekielRaiden
Follower of the Way
I would take it in a direction similar to games Powered by the Apocalypse, such as Dungeon World. That is, I'd consider the core concepts and commitments of such an archetype, and try to figure out how that archetype would both be reasonably manifested (e.g., what things demonstrate being that archetype) and fittingly challenged (e.g., what situations or questions would naturally arise from that archetype.)A class isn't only a list of class features, but also the marks of identity, and also the subclasses should show their themself.
I propose an exercise of imagination:
Thanks a collab between WotC and Japanese novel self-publishing website Shōsetsuka ni Narō there is a literary contest. It has to be a story about a character from Kamigawa: Neon Dinasty who is killed during the Phyrexian invasion (let's be more original than the isekai trope of hit by a truck) and (s)he is reincarnated within a D&D world. This character becomes a warlord, with a group of allies (a harem of monster girls if you want). The goal is to create a warlord character so interesting than players want to play with this new class.
How would you design this warlord? It will be for a "litRPG", and then the background of the character(s) is more important than the gameplay.
The Warlord is a student of war, in some form. They learn from it, adapt to it, experiment with it, and get tested by it. Even if they're terrible at actual chess, they have to be able to predict the beliefs and actions of others in order to be effective. They need to have some understanding of goals and motivations, and how to manipulate them. But a manipulator is also distrusted, while a leader must be trusted. That creates an inherent dichotomy. How does the Warlord balance the undeniable utility of guile with the absolute necessity of trust? Can they thread the needle between loyalty and mind-games?
The Warlord is also a facilitator. They are at their best, not when they do things on their own, but when they leverage allies' strengths to new heights, and exploit enemies' weaknesses with cunning and guile. But that also means the Warlord is, in a sense, unnecessary. If their allies could just tap that power and see the weaknesses on their own, would they even need the Warlord? Having a specialist is great, sure, but there's an internal conflict there, needing others without necessarily being needed yourself. Resolving that conflict is likely to be a long-term thing.
I made a Batman comparison earlier, and I really wasn't joking. Many of these things are themes explored in Batman: the Animated Series.