Higher Female Protagonist Voice Mod
MODSeveral choices of higher-pitched tweaks of the vanilla female protagonist's voice.
Add the name of the esp file of your chosen voice type (for example: "Higher Female Protagonist Voice - Type D1.esp") to the plugins.txt file, which is typically located in C:\Users\(your username)\AppData\Local\Fallout4.
These qualities, while not problematic if you're supposed to be middle-aged, are incompatible with the perception of a young-sounding voice, and it is effectively impossible to simply change them or edit them out.