I remember there is a way to do this, but it isn’t super well documented and involves having sprite frames with specific names. Unfortunately, I do not remember what the names are anymore 😓
(I might be misremembering with the AnimatedSprite node, thinking about it…)
You might want to check on GitHub by searching “Sprite3D Normal” and see if you can find a discussion on it in closed issues/PRs.
I want to say the setup is: make an normal sprite frame and give it a name, and then make another sprite frame called “name_Normal”, where name is the name of the sprite frame.