Voronoi fracture
The go-to way of breaking a model into believable shards: scatter points, and let each point's Voronoi cell become a piece.
Seed points are scattered through a mesh — denser where a bullet or blast is meant to hit — and the Voronoi diagram is computed. Each cell is clipped against the model's surface and becomes its own fragment. The cells are convex by definition, which is exactly what a physics engine wants: every chunk can become a rigid body with a cheap convex collision hull instead of an expensive arbitrary shape.
The cutting is usually done ahead of time in tools like Houdini or Blender's Cell Fracture, and the game swaps in the pre-made shards when something breaks. Unreal's Chaos Destruction (2019) and Nvidia's Blast build hierarchies of fragments so a wall can split into big blocks first and crumble further later. It looks great on concrete and glass, less so on wood, which stubbornly refuses to shatter like a crystal.