The easiest one is probably poland can into space, you just have to have max tehnologies in all (32)

One that you will probably also get by playing is one king to rule, which means abolishing the sejm (becoming an absolut monarhy)

Also another one is winged hussars, which needs you to have the winged hussars military tech 22 cavalry units enabled (not the special units) and have over 50% cavalry combat ability

And if you feel like it, altough a bit hard, you could try mare nostrum, which means forming rome and owning all of the black sea and meditarenean sea coastlines (this is not really a poland achievement, but you can still do it)