I looked-up many references and websites and researched on how to determine if a method is between parametric or non-parametric. I came up with below definitions,
A parametric algorithm has a fixed number of parameters. In contrast, a non-parametric algorithm uses a flexible number of parameters, and the number of parameters often grows as it learns from more data.
Moreover, I found,
A parametric model, we have a finite number of parameters, and in nonparametric models, the number of parameters is (potentially) infinite.
From https://sebastianraschka.com/faq/docs/parametric_vs_nonparametric.html.
And many other methods of determination, though the problem is none of them can helo ones to determine if a certain hypothetical method is parametric or not. (For instance, why k-means' number of parameters are constant but KNN is variable or basically what do we call a parameter and what we do not?)