Saiukia's Buff Gui includes a /buff command which will open a gui that includes health, stamina, oxygen, and other buffs, as well as damage which you can adjust as you like! this mod is client side and server side too! meaning you can install this on your world OR your server! 

THIS MOD WAS MADE WITH COMPLETE AI SLOP CODING! SOURCE CODE IS PROVIDED!

For Local worlds make sure to enable the mod in the world settings, if you wish to use the mod!