Multi Level Indexing using ElasticSearch

The thing is I am a student and I am working on an educational platform that will have a knowledge map of all domains and subdomains within the domain of education itself.

Now, for the application we are developing, search is a major feature and hence we are considering ElasticSearch but the problem that i have in understanding is that can we have multiple levels of indexes/types?

Meaning can we have a heirarchy like

-Human Anatomy
-Non Aquatic

and so on.. basically what I am trying to achieve is having multiple indexes (I know that this is not a problem) and each of them have undefined number of types (I know even that is not a problem) but then each of the types can have an undefined number of types as well. I could not find anything specific to this in the documentation or any video. If you can point me to the right source, that will be very helpful.