i am woundering how i would go about giving players full health/food/water after killing another player or if there is a plugin what does this thanks.

If you check the plugins list you will see there is a plugin that "robs" victim of health (etc ?) when you kill them, I use "wellfed" plugin to give players full health/water/food when spawning/respawinng as i hate the very low (have to find food) startup that is default,

maybe you search for this ?
https://umod.org/plugins/life-stealer

maybe who knows xD