Putting Model Hair on a Starter Character?

Okay. You don't need any script for this:

step 1: Make sure you have a hair equipped on your avatar;

step 2: Play your game in the studio;

step 3: Go into your character by the explorer and find the accessory that is named with your equipped hair's name;

step 4: Copy it (Ctrl + C) (COPY THE ACCESSORY, NOT ITS NAME!);

step 5: Stop playing;

step 6: Go in StarterPlayer > StarterCharacterScripts and then paste what you've copied (Ctrl + V)

Yep, that's it! You might wonder why I choose to insert the accessory in StarterCharacterScripts. Because the game automatically inserts what's in StarterCharacterScripts in the character of the player. The game will not check if it's a script or not.

In the accessory, you will see a child named "Handle". You cannot change the "Handle" 's name. However, you can change the accessory's name. In that "Handle", you will see a child named "Mesh". You can go to the catalog and find some hair IDs and copy / paste it in Mesh.MeshId.

Hope this helped!