This question has been asked before. Searching things up in the forums is faster than waiting on someone. https://forums.pmmp.io/threads/spawning-an-entity.6477/
hi i got u a plugin that worked for me but i dont know if it will work for your api if u do /irongolem it will spawn a irongolem on your position tell me if it works becuase i dont have 3.12.2 github:https://github.com/Jviguy/IronGolemSpawnCommand