Okay I was required to add a bool out just to get the function “SetHeadScale” to show up in the animblueprint.
What I did from there is create a new State so I have access to Modify Bone node.
Then I hooked the state up into my flow like so (Im not sure if this is “correct”).
I simply put a tick in the bCanEnterTransition to Run/Idle, perhaps there is an issue there.
Ive looked at what you said about ModifyBone node needing a pose and gave it a Mesh Space Ref Pose but I have no idea if thats the correct one. It doesnt seem to do anything currently when I call SetHeadScale from my Character.