There is no universal "walk through walls" cheat code that works across all video games. Cheat codes are specific to individual titles and often tied to specific platforms—a code for the PC version of a game typically won't work on the console version.
Activation methods differ wildly: some require keyboard sequences, others need specific controller button combinations, and many modern games require external trainers or mods.
Note: While cheats can be fun for experimentation, they often diminish the intended challenge and satisfaction of gameplay. For those interested in the technical side, researching "game modding" or "memory editing" offers deeper insight into how these codes function.