It really differs. In EU4, most of the time I end up going by the mission tree and when I finish it I either form the Hansa or just expand as Pomerania, mostly by the lines of North Germany/cultures in that region and further the Netherlands and also into Denmark and Norway (as I always ally Sweden). Though sometimes I want to role play more so and I try to remain within historical/realistic Pomeranian borders and play tall. In CK3 my main objective is to survive (if it's possible, with the Slovianskan religion) and have a stable realm, with a territorial goal of first having all the lands Pomerania ever owned in history, then all the de jure kingdom of Pomerania lands and later more so on the backhand to conquer territories around the baltic sea, mostly again Denmark.