There can be various causes of variability and to find out which parameters have the greatest influence on the process and to what extent specific experimental production tests can be programmed to observe the behavior of the system and understand which parameters most influence the qualities that affect the product.
There are various Design Of Experiment (DOE) schemes that can be used, so it is a question of choosing the most appropriate scheme for your operating conditions (number of parameters, levels, restrictions, etc.).
An example of 2-factor and 2-level experimentation looks like this:
to which the statistical analysis of the results must be associated in order to be able to act appropriately on the system.