I am knowledgeable about several topics - a phrase/adjective to describe this with respect to the topics? [closed]
Those topics can be said to be “in his wheelhouse”
Defined in Dictionary.com as:
within one’s area of expertise or interest:
There are some subjects that are in your wheelhouse and some that are not.
They are his or her specialities.
Specialty = a subject that someone knows a lot about
Cambridge doctionary