Iron Golem

I'd suggest watching tutorials on YouTube, as well as reading up on the tutorials here on the MCreator website. Especially searching through the forum to find other topics related to yours. Creating a custom entity is one of the basic elements of MCreator, so definitely check out tutorials online. You could make a custom model and texture in blockbench, import them in MCreator, then apply that model and texture to your custom living entity. That's how you make any custom entity.

I am currently working on a tutorial on how to create iron golem-like mobs.

Golem like mobs reequire a high priority task called DefendVillageTargetGoal

Klemen has said might consider this down the road.

hi im reggie!, i'm new here .. so i have doubts on how to make a mob spawnar in the same way that an iron golem would spawn or a wither. like placing blocks and making a structure with blocks as in the case of iron golem