In my game, I want a character to have certain emotions depending on what choices you make, and have different endings depending on which emotion they feel at the end. How would I do this?

https://cloudnovel.net/documentation/novel/advanced/introduction-to-flags

You should use string flags with the mood you wanted (sad, happy...).

On your end scene, you just use conditions on pages so the player will just see the pages needed.

IE: END SCENE

Page 1 condition sadmood
Page 2 condition happymood



You can also do it with screens, adding conditions on screens so the only screens that will show are the end related to the mood you want.