Possible to change constraints stiffness, damping, breakable during runtime?

For skeletal meahes, Unless they removed or broke them you should really just be using ragdoll profiles and swapping between the predefinitions you make rather than setting things as a one off via code.

It’s not only best practice, its going to save you from feeling like an id1ot when you can’t figure out why x joint is stiffer than Y after a day of looking at it due to some lost code function that you called in a forgotten one off…

For the other stuff you are kind of stuck to the code, but you can centralize it the same way.
Create a c++ component class, make the function avaliable within the class. Attach the component you created to the object you want to control, then call the component’s function.
Its still a one off, but you can search references to the class to hopefully find the issue on the fly.