If you get a potion with Instant health 125 or above, it instantly kills players in creative, survival, and adventure mode. Your death message also doesn't appear, and it doesn't count as a real death.

 

Give command for this potion

/give @p splash_potion{custom_potion_effects:[

{id:"minecraft:instant_health",amplifier:125b,duration:1,show_particles:0b}

]} 1

Also with the Affects versions there are a lot more versions, but all I can do are those 2