The real question is how did you get it to not follow. Normally this just works without any messing around.

Is the hair actually parented to Homme's head?

And, is the shirt Conformed to Him?

That should be all it takes to make a figure's body scales propagate to conformed and parented objects. It won't hurt to just re-attrach the hair and shirt.

Set the figure's BODY scale to 100%. Select the hair. Then Top meny > Object > Change Parent ... then choose His head.

For the shirt select the body of the shirt. Top menu > Figure > Conform To ... then choose l'Homme.