Well there are all sorts of methods of raising power, but afaik this isn’t like a product (so to speak) that exists that you can just do the method and bam, demonic energy.
Maybe the stuff in the Path of Smoke will help? https://forum.becomealivinggod.com/c/kurtis-joseph
I say this because working with Ahriman and Azi Dahaka on my chakras changed my energy significantly.