Yes, there is an optimum range of T for the effects. The goal (for most) is to create or mimic the same measurable levels of hormones that occur in healthy men who are not trans & do not have other conditions.
It will be a personalized/individualized dosage that will produce these results.
There are so many factors about how your body handles synthesized hormones that are unique to you. For example, you have a certain number of androgen receptors cells. That varies by the person. The number of cells capable of funneling T and making it useful for the body is limited by this number. Also, different people have different sensitivity in their androgen receptors. More sensitive androgen receptors produce more androgenic effects with less 'fuel.'
Finding the 'right' dose is definitely a trial & error system of dialing in on what your body does and monitoring. But since your body is always changing as you age and in response to other things happening to you (physiologically, your environment, your behavior), it isn't even correct to say that you have one idealized dose. You theoretically could find *one* idealized dose for NOW, and that may change over time too. You have to be monitoring and adjusting to optimize the dosage holy grail.