How to click a button to make you spawn as a custom model?

Alright, so I am making a roleplay game and I have some custom models that were made in blender. You can pick the age of your custom model, but I have no idea how to code it. So there’s an “Adult” and a “Child” option and when you click one of those buttons you’re going to spawn you in as the custom model. If this is confusing please tell me!