Maxis never released official cheat codes for Spore. What you'll find online are community-discovered exploits—glitches that manipulate the game's systems in unintended ways. They're not supported, they can corrupt saves, and they may ruin the experience the designers crafted.
Spore is about creativity and discovery. Exploits shortcut the progression that makes each stage meaningful. They also risk save-file corruption, leaving you with a broken galaxy. For the best experience, embrace the limitations—they're what make your creations uniquely yours.