Blacklist Specific Mobs from Being Flattened
Accessing the Config File
Locate your mod's config file in the .minecraft/config folder. Open the Flatter Entities configuration file in a text editor.
Adding Mobs to the Blacklist
Find the blacklist section in the config. Add the internal names of mobs you want to keep in their normal 3D form. For example, if you want certain boss mobs or decorative entities to remain three-dimensional, list them here.
Each mob should be entered on its own line or in the format specified by the config file. Use the exact internal mob identifier (the namespace ID used by Minecraft and mods).
Saving and Reloading
Save the config file. Restart your game or use a reload command if the mod supports hot-reloading. The blacklisted mobs will now render normally while others remain flattened.
Tip: If you're unsure of a mob's internal name, check the mod's documentation or hover over mobs in creative mode to see their identifiers.