Demo Link
This asset is a Low and High Polygon Chain Prefab, each link is fully configured with collider and joint to make up a physics interactive chain.
This asset was created using the Unity default physics engine. For best result set "Physics Solver Iterations" to about 50 (Edit>Project Settings>Physics).
This Asset has multiple presets to show real-time physics ability of the chain and basic instructions. The chain section can easily be scaled (Configurable Joint is best) and or duplicated and then joint connected to extend the chain length. Please also refer to the solver section of the documentation for smaller scale chain links.