There is no "kid cheat" in Grand Theft Auto: San Andreas. The game does not feature children as NPCs or playable characters, and no cheat code spawns, transforms, or interacts with children.
Legitimate cheats affect weapons, health, wanted level, vehicles, weather, time. Full list on IGN or GTABase.
Reminder: Using mods/cheats in GTA Online (not applicable to SA single-player) risks ban. Single-player: play however you want.