You know how to create ? İ need this
Do the main quest in the game.
Here's a completely unconfirmed hypothesis which I believe would make you a faction leader...
1. Join the biggest faction in the game and wipe out one of the other faction territories.
2. Now keep finding the leader of that obliterated faction and fighting them.
3. (Make sure hero deaths are enabled.) Kill the leader of that little faction. Keep doing that until only ONE of the leader's clan remains and they are now the leader of that faction. At this point, turn hero deaths back off.
4. Now you'll be -100 relation with the leader of that Clan. Join that faction now. (Note: If they won't let you join because they hate you, you may need to keep fighting the leader and any remaining vassals over and over again and releasing them until you're in good enough relations with them again.)
5. Once inside of that faction, do things that earn you influence, like helping them reclaim some territory that you previously took from them.
6. Once you have enough influence, raise everyone in the Clan except the leader to Relation 100. If it was only the leader left, that's fine, skip this part.
7. Enable hero deaths again and stay out of trouble until the leader of your clan ends up crossing swords with the wrong person and gets executed by one of the other factions.
8. You should now theoretically be leader of the faction you joined, which should give you the full control over that faction as though you had made your own. You should now have the power to rename it, but you'll still be locked in to whatever color they always had. Make sure to turn hero deaths back off.