[debergalis]

Yes, the lead raises the effective octane, preventing detonation. The other tool for preventing detonation is running extremely rich fuel/air ratios, the typical setup for the airplane at full takeoff power.

You target an appropriately rich mixture at sea level when tuning the carb or adjusting fuel flow for injected engines. The pilot manually leans the mixture as the aircraft climbs to maintain a reasonable fuel/air ratio.

Owners sometimes call that mixture lever the money lever because it governs fuel flow, aka "dollars spent per minute".