You’re spawning an actor at a specific location in world space. This will not parent the actor to the player character. I would suggest opening your mannequin’s skeletal mesh asset, right clicking on the head bone in the skeleton hierarchy, and selecting “Add Socket”. Set the relative location of the socket to your liking and save the asset.
Go into your character blueprint and start your “EquipItemOnServ” event with a branch, using “IsEquipped” as your condition.
If false, SpawnActor(BP_Bag) → Set Collision Enabled (Target is return value of Get Actor of Class, New Type is No Collision) → Attach Component to Component (Target is the skeletal mesh component of the aforementioned return value, Parent is your character’s skeletal mesh component, Socket Name is headSocket (case sensitive), and the “Rules” should all be set to Snap to Target → Set “IsEquipped” to true.
If the branch at the beginning of your event returns true, Destroy Actor (BP_Bag) → Set IsEquipped to false.