Level: EasyChoose a person you want or just create one with good diplomacy traits and try to get as much prestige as you can get. Create titles and use hunting and fests for extra prestige. For me (Bayek) it took 5000 prestige every time so wait and then create a divergent culture in your culture menu.
Alternatively, start as one of the Duke vassals of the Byzantine Empire. Most of them can create a divergent culture from the start if they only change ethos.
Credit to
Bayek von Kuwaq on Steam for his
guide. Information sourced from the
wiki.