I haven't started trying yet but I have the basics of how remote works and I think you use that to communicate between client and server with Filtering Enabled.
I just need some hint or tips on how that would be possible. Maybe a short code I could take a look to have some idea on how a GUI hat giver would work? Because I would want everyone to see the hat, not just show it locally. Thanks again.

3 comments
You can see of functions to Acessory's in wiki: remove: https://developer.roblox.com/api-reference/function/Humanoid/RemoveAccessories add accessory: https://developer.roblox.com/api-reference/function/Humanoid/AddAccessory
i will try to post a answer.
because you dont want it local, im guessing you might need remote events