This data pack changes skeletons to undeads.
undeads have a 10% chance to drop a knowledge book, 9 knowledge books in a crafting table make op armour .

place down a repeating command block, always active and inside it /function finster:kickstart
then place down a repeating command block, always active and inside /clear @p command_block. then put a coparator getting an output from the second command block and connected to the comparator, a impuse command block, needs redstone and inside, /execute as username run function finster:opme

REPEAT FOR EVERYONE ON YOUR REALM/SERVER IF YOUR ON ONE

If it dose not work, trust me I tested everything