HOW TO MAKE Grass Swap unreal ref Kena: Bridge of Spirits

If I understand correctly, you ask how you change the texture or material information like in the gif?
It is a big sphere mask, that is uses lerp or step to hides another texture.

The base effect is described in this mini tutorial:

I have used this technique in a challenge sketch some time ago: Mathew Varkki: Sketch #18 WIP - #8 by raytheonly

You will need a script or Blueprint, that drives the value and provides world location information for the material.
There are many layers to the effect In the Kena reference.

  1. Initial burst with particles and refractive distortion
  2. Grass spawning
  3. Flowers grow
  4. Part of trees dissolve.
    All of these materials have to be driven by the same parameters. But some of these have an offset, that they start later.

I hope this helps you.