Behind the scenes… I’m going to tell you how do to /summon. Type: /summon iron_golem. If you do that, it will simply summon the iron golem instead of building it and getting spawn eggs. Although you have to type it.
You can also do /summon lightning_bolt. You need to make the “_” In every two words. Like snow golem would turn into Snow_golem. But you need to make sure to put the under slash in every two separate words. One more example: end crystal turns into ender_crystal.