Once you solve a docplex model, it creates an internal SolveDetails object that contains the best bound you're looking for. You can access it in two ways:
Assuming you've defined your docplex model as model (an instance of the class docplex.mp.model.Model)
Assuming you've stored your model's solution in sol (an ...
ILOG Cplex 20.1 installation comes with a directory with examples. To use the conflict refiner, you want to consult the manual which includes a list of files that contain examples on how to use the conflict refiner. Of particular interest are the following files: