This is just a port of hokage3211's Spider Queen Boss BattIe One Command creation to upper versions like 1.14 and 1.15 as a datapack.
All info comes from this page (Please show some love and support to its original creator): www.planetminecraft.com/project/spider-queen-boss-battle-18/
(Ocelots and cats have been separated into their own mobs so if you want to make a Spider Cat pet, do it on a cat instead of an ocelot.)
Enjoy! 😄