Aircraft horns do exist, but they are not utilized in the same way as car horns. The main use of airplane horns is to help with communication between ground staff and the flight crew. The buttons in the cockpit sound these horns, which are usually mounted on the plane's nose. Over the roar of the engines and other aircraft hardware, the horn's loud, piercing sound may be heard.

There can be many uses for airplane horns including,When the plane  ready for departure or when it has safely landed and is ready to taxi to the gate, ground crew members will sound the horn to notify the flight crew.

Horn can be used to alert ground personnel to any potential dangers or obstructions on the runway or taxiway.

The horn is used to communicate between the flight crew and the ground crew during pushback from the gate and when the aircraft is being towed in order to ensure secure flight.

by applying the horn to notify nearby aircraft of the presence of the taxiing aircraft is sometimes viable.

Therefore, although airplanes have horns, they are largely utilized for aviation safety and communication rather than the same reasons as car horns.