As I understand it, 'fine tuning' is simply a fact of the universe: that the fundamental constants have values that allow for the emergence of complexity, and that even slight changes to those values would lead to homogeneous and featureless universe. I don't have the physics background to demonstrate this for myself, but I believe it.
To then reason from that fact to the existence of a multiverse or the existence of God is an extra step that one need not take, but not taking either of those steps doesn't invalidate the appearance that the fundamental constants of the universe were fine tuned for the production of complexity/life.
As I understand it, 'fine tuning' is simply a fact of the universe: that the fundamental constants have values that allow for the emergence of complexity, and that even slight changes to those values would lead to homogeneous and featureless universe. I don't have the physics background to demonstrate this for myself, but I believe it.
To then reason from that fact to the existence of a multiverse or the existence of God is an extra step that one need not take, but not taking either of those steps doesn't invalidate the appearance that the fundamental constants of the universe were fine tuned for the production of complexity/life.