Draw XXL
Link to documentation.
Link to Unity Asset Store entry.
Draw XXL is an extensive set of visual debugging and development tools for the Unity 3D engine. It can be used as components without any code or like debug lines as one-line-calls from anywhere in your code.
Whether you are just looking to increase your options from Unitys limited Debug.DrawLine(), learn some more about the Game Engine by visualizing basics like quaternion and euler rotations or boost your productivity with charts or physics visualization: Draw XXL got it covered.