Since all holdings (barony level holdings) are now on the map and you'll most likely be able to play as low nobles that hold a single castle, I've been thinking of how the title system could work. In CKII you had titles based off top level holdings (counties) and groups of these top level holdings (dukedoms) and groups of those and so on making kingdoms and empires. I feel like this doesn't really work in the sense of what a title is.
Take Normandy for example, before the vikings raided Francia, Normandy wasn't a thing, it was just the northern coast of Francia. When the duchy was created, it was only granted the lands of Rouen and those surrounding it, making up what is now known as Upper Normandy. In CKII we can't move de jure counties from one duchy to another and I feel like that impacts gameplay somewhat, so if the first instance of the duchy of Normandy was used for the de jure counties, what would hold the other half of Normandy? Things like this could be overcome with a new title system.
As for how we implement a similar system into the game, there should be a way to "create a title" or "grant a title" that allows you to select certain provinces like how you'd select provinces after a war in EUIV that will be made a part of a new title such as a county, or duchy or similar level title. These provinces would then be a "de jure" part of that title unless the title was destroyed or unused for a certain amount of time, such as how de jure drift works in CKII, duchies and kingdoms can move between higher level titles.
As for Kingdom level titles, you'd need a certain percentage of provinces from a culture that you wanted to make a kingdom for, such as 80% of all Anglo-Saxon lands controlled to create the Kingdom of England giving the character a special nickname specific to the culture, King of the Franks, King of the Lombards etc. and as for emperor level titles it'd be similar to kingdoms except a much higher cost with probably like 95% - 100% of provinces of that culture controlled.
Take Normandy for example, before the vikings raided Francia, Normandy wasn't a thing, it was just the northern coast of Francia. When the duchy was created, it was only granted the lands of Rouen and those surrounding it, making up what is now known as Upper Normandy. In CKII we can't move de jure counties from one duchy to another and I feel like that impacts gameplay somewhat, so if the first instance of the duchy of Normandy was used for the de jure counties, what would hold the other half of Normandy? Things like this could be overcome with a new title system.
As for how we implement a similar system into the game, there should be a way to "create a title" or "grant a title" that allows you to select certain provinces like how you'd select provinces after a war in EUIV that will be made a part of a new title such as a county, or duchy or similar level title. These provinces would then be a "de jure" part of that title unless the title was destroyed or unused for a certain amount of time, such as how de jure drift works in CKII, duchies and kingdoms can move between higher level titles.
As for Kingdom level titles, you'd need a certain percentage of provinces from a culture that you wanted to make a kingdom for, such as 80% of all Anglo-Saxon lands controlled to create the Kingdom of England giving the character a special nickname specific to the culture, King of the Franks, King of the Lombards etc. and as for emperor level titles it'd be similar to kingdoms except a much higher cost with probably like 95% - 100% of provinces of that culture controlled.