Is the Amazing Destruction (Yveltal) knock out an effect or part of the attack?
Shining Fates Amazing Rare Yveltal has the following attack text:
Your opponent’s Active Pokémon is Knocked Out.
That is an attack, and the effect of that attack is that the opponent’s Pokémon is knocked out. A Pokémon that was protected from the effects of attacks would be protected from that; it is not dealing damage.