Question Making growing objects while walking around?

I want to make it so that when my player walks on a plane I want to start growing plants around the player. I don't want to instantiate a prefab or something like that. What would I need to study to do such a thing?

 

For some inspiration, you might want to take a look at the GDC talk "Restoring the Forest: Capturing the Themes of 'Kena' Through VFX" (in particular at 10:06)). It's Unreal, but some of the ideas could translate. They used the blue channel to scale up foliage materials from zero. They also have some examples of what happens with larger assets.

I'd imagine something similar could be done with scaling prefabs that are already placed, or with a custom shader in shader graph, influenced by the proximity of the player.