This package provides a shader and accompanying scripts that make it easy to prevent text from rendering through walls.
Place a normal 3D Text component into your scene, then add a Font 3D component to the object. This will automatically make all needed material and shader changes, and keep these up to date whenever you change the font or color of your text.
If you need to change your text's color at runtime, be sure to change the object's Material color, not it's TextMesh color.