Here’s a good read: Inigo Quilez: domain warping - 2002.
I wouldn’t over-work the phrase “Domain Warping” into anything deep and mysterious that only a few cognoscenti know; creative play with the venerable warp command, and/or the various warp_* variants can get you tickets into this game. Say, start with Perlin noise for the base image. Twist, rotate, displace, as if mixing paint with (maybe a dynamically changing) warp displacement field, noise ⇒ warp ⇒ repeat, and you are “domain warping.” We’ve all done this; maybe we didn’t know at the time that the Chattering Classes had given it a fancy name.
Reminds me of this thread from a few years ago: Can G’MIC do those kind of textures?