Change model of entity while entity is spawned?

Is there any way of changing the model of an entity while the entity is spawned? Let me give you an example:

This is a gamemode called “Real-Life”. Its not that good, sometimes even depression, off-topic. It got this entity called “humans”, which have 5 stages. Stage 1: Baby, Stage 2: Teenager, Stage 3: Adult, Stage 4: Old, Stage 5: Dead.
The entity will despawn at stage 5, but a baby dosen’t look like an old man, so the entity have to change model each time it goes up one stage. I could only really think of one way of does this, which would be making 5 entitys called:
humans_stage1, humans_stage2 and so, but that would be unpractical if the init.lua would be the same all along, but simply the model would change. Is there any way of keeping it within 1 entity whilst changing model? Kinda like some of the RP drug plant mods do.

Thanks in advance
BTW: That gamemode was complete fiction, not actually gonna make that lol.

Entity:SetModel(“something.mdl”)

Thank you so much. I really could not find anything about this