I write in English as I presume you intend to take the programme(s) in the language:
I am attending Leiden university and the answer in short would be: Yes. However, you should keep in mind that there are mainly two types of instruction: (1) lectures and (2) seminars/work groups.
(1) Most of the lectures at Leiden are unilateral, meaning you will simply be listening. In some cases, there will be hundreds of students listening to one lecture, and, of course, interaction may occasionally take place, but there will not be large discussions;
(2) In the seminars however, you will be exposed to a number of discussions and debates, for which you will be asked to prepare.
This is the case in most faculties, including International Relations and Organisations Bsc and International Studies BA (if you intend to learn politics in English); if graduate degree then there should be more possibilities for discussion during class, as the participants in class are also lower in number.
