

Inside Out is a great example of just that. While I couldn’t find the scene, here’s an excerpt from tvtropes.com:
*Entering the Abstract Thought Chamber in Inside Out caused the characters to turn into 2D figures with increasingly less defined shapes. *
If I remember correctly, the characters actually acknowledge the shift to less detailed artstyles.
Alright so, TLauncher is owned by a big bad Russian company, buuuut they were a pillar of my early-ish childhood thanks to free Minecraft, so yeah, your choice.