can I set aa audible reminder 2hours before my appointment without changing the alotted time

I believe you're much better off using the Calendar app if you want that.

Go into the Calendar app, tap on the + in the upper right, type name, add location if you want drive time considered.. then you can select Alert, and then Second Alert will appear.

I do this often because I want a reminder the day before and then a couple hours prior

Create and edit events in Calendar on iPhone - Apple Support