How to make spawning animation like the warden

Hi, I'm using the GeckoLib Plugin and Mcreator 2024.3, and I don't know how to make my entity do the spawning animation like the warden. I see many people spawning an alt entity with the appearance of the main entity, then letting it do the idle animation before despawning it and spawning the main one right after. But is there any other way of doing this? Like making the entity play an animation using procedure instead of the [Animation] tab?