Now I usually play as the Demogorgon so I don't usually notice but, I was once pitched against it as Big Steve when I noticed it had the default Heartbeat. I was kinda disappointed coz a few other killers have their own, like Myers had the Halloween theme, or a version of it, so i thought that perhaps they would have done something for the Demogorgon. So I was wondering what the availability is of using The Upside Down - Kyle Dixon and Michael Stein from 2:20 onwards as it gets increasingly more intense and has a deeper undertone.

TLDR: my suggestion is The Upside Down by Kyle Dixon and Michael Stein from 2:20 onwards.