Victoria 2 I must admit goes a bit above my head. But I get the impression in Vic2 that you would be able to have an entertaining game with a smaller power, with a country that has few or no colonies, just because of internal mechanics, economy, industry, social development, etc.
One particularly nice thing in Victoria 2 is that it's actually possible to take a country that starts out very "backwards", like Spain (virtually no industry, very bad literacy) and over the course of the game develop it into a high tech, industrialized, powerful country rather than having it lag as it historically did; and you don't need to blob across colonies, or even maintain Spain's existing colonies, to do this - your core territories are enough to hang on to GP status and finish in the top 4. The downside to this is that doing so basically just involves pushing Encourage Bureacrats until your admin efficiency is up, then getting all your populous states to 2.0% Intellectuals, then getting them to 4.0% Intellectuals, then encouraging Craftsmen. It's not very involved gameplay and mostly just feels like observer mode if that's all you're doing. That said, the fact that you can do it at all is great, and if the process had more active player involvement then it would be a great way to have gameplay that supports building tall.
You can of course do the same thing while building a large empire, but this doesn't actually benefit your country as much as you might think, especially if you're playing on a mod that enables colony costs. The main advantages are getting more direct access to certain goods, and having more shipyards to raise your naval cap / lengthen your supply distance. It won't directly raise your industry score, and the number of soldiers you can recruit is, in most mods, fairly limited. Colonies are mostly about map painting / having a big empire to point at, and in all honesty the highest industrial scores I've managed have always been in games where I didn't bother colonizing much or at all, and instead focused on cycling national focuses, expanding factories, manually building factories for same-state input bonuses, and trimming unprofitable factories.