https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/entity/ArmorStand.html setBoots(ItemStack) setChestplate(ItemStack) setHelmet(ItemStack) setItemInHand(ItemStack) setLeggings(ItemStack)
You may be able to cancel clientbound sound packets using ProtocolLib. It's a bit more tedious than Nemo's method, but it's a lot cleaner in terms of what the player will see.
This is working fine, you don't see the armorstand teleporting, probably cause it is in the same tick. But it works thanks
At the beginning I tested by using setSilent(true), but forgot to change the variable part so I thought it didn't work. But setSilent(true) works