The most popular 7 chakra system has only been invented/discovered somewhere between 1200 and 1600. Before that there are some mentions of 3 chakra centers which resemble the 3 dan tiens in chinese medicine.

Now I may go out on a limb here, but the way I make sense of the chacra's is that they are useful concepts to connect to certain aspects that make sense to group together. As such you can get a "higher" working package and influence that structure to the benefit of it's parts..

So yes in that sense every chacra is a portal/gateway to some realm which governs the chacric base concept. For those that see soul as a spark of devine love the heart chacra can be used to focus on and gain acces to that realm.

In my understanding imagination and belief provide the "power" if you will to make such a connection.

With Love
Eelco