Encrypted mods are specifically designed to prevent unauthorized extraction. They often manifest as when users attempt to force open or modify them.
If the file is a standard .kn5 that isn't locked by a third-party encryption tool, you can extract its contents (textures and .fbx models) using Content Manager : how to decrypt kn5 files exclusive
Once Developer Mode is active, you can export the file to a readable 3D format: how to decrypt kn5 files exclusive
If a file isn't heavily encrypted, you can often "unpack" it directly into an editable format (like .fbx ) using . how to decrypt kn5 files exclusive