Changing Unified heightmaps at runtime?

Is it possible to change Unified heightmaps at runtime? I tried Physics.unifiedHeightmaps but it's not working...

I was testing some stuff and in my case when I don't use Unified heightmaps my character is a lot less shaky when moving on terrain colliders compared to when I'm using Unified heightmaps. But then I realized that while not using Unified heightmaps the collider collisions are a lot less precise so I'd need to turn it on and off at certain moments in my game.

Thanks