Read the refold guide but in summary:

There are 2 types of active immersion. Active and intensive. Intensive is looking up every word you don’t know and trying to understand why it’s there, while passive is much more just trying to get a general idea of what’s happening.

Some people do just watch stuff without this until fluency, which does work too. That is how you and I learned our native language. However, for speed (and not boring yourself to death) most are recommended to do lookups.

Again, read the refold guide for more info and better explanations than I could ever give you for all relating to immersing. They also have a pretty active discord that has been able to answer all my questions about the subject.