There are following royal titles and royal career paths in 2.3 (all listed titles appear in game instead of vanilla "Faction leader" trait):
Imam
available for: Omanis
effects: +2 Authority, +3 Law, +3 Personal Security, +3 Public Security, +3 Tax Collection
Khalifa
available for: Abbasids
effects: +2 Authority, +3 Law, +3 Personal Security, +3 Public Security, +3 Tax Collection
Malik al-Mu'azzam:
available for: Sumras
effects: +2 Authority, +2 Law, +3 Personal Security, +3 Public Security, +2 Tax Collection
conditions to obtain: Treasury of at least of 10000, Global standing 0.0, Chivalry at least 3, Piety at least 1, Possession of 6 settlements (including Kolachee, Mansura, Sukkur and Thatta).
This title is pre-requisite for Sumras to gain Sultan title!
Khwarezmshah:
available for: all Islamic factions
effects: +2 Authority, +3 Law, -3 Loyalty, +4 Personal Security, +2 Tax Collection
conditions to obtain: Treasury of at least of 5000, Chivalry at least 1, Piety at least 1, Possession of Urgench and Khiva.
This title is pre-requisite for Khwarezmshahs to gain Sultan title!
Sultan
available for: Ayyubids, Ghaznavids, Ghurids, Khwarezmshahs, Seljuks of Iraq, Seljuks of Rum, Sumras
effects: +2 Authority, +3 Law, +3 Personal Security, +3 Public Security, +3 Tax Collection
conditions to obtain: Treasury of at least of 30000, Global standing 0.0, Chivalry at least 5, Piety at least 3, Possession of 8 settlements
Sultan al-Mu'azzam
available for: Ayyubids, Ghaznavids, Ghurids, Khwarezmshahs, Seljuks of Iraq, Seljuks of Rum, Sumras
effects: +3 Authority, +4 Law, +4 Personal Security, +4 Public Security, +4 Tax Collection
conditions to obtain: Treasury of at least of 50000, Global standing 0.0, Chivalry at least 5, Piety at least 4, Possession of 12 settlements