Zoom view by Timeline using external float values

I have a Timeline to control player’s FOV/zoom by the button (pressed - zoom, released - unzoom). Everything works fine, but there is one unpleasant problem - in my Settings Menu I have a slider to control the default FOV of the player. Therefore, the FOV can be specified in a wide range (in my case between 30 and 120). But I can’t pass that value into the Timeline. External curve also does not help because there is also no access to the current selected player’s FOV. I can use only predefined/hardcoded values of the curve, but not those that I want to read from the specified by player values. Is there any possibility to implement such a task? Thank you!