Has a patent been applied for for the four wheels of the car?

Even if there is an application, it has expired and become existing technology.

There are also cars with four wheels that evolved from the original horse-drawn carriages. Please see the history of cars below:

In 1672, the Belgian missionary Nan Huairen created steam in Beijing. Powered mechanical device, a three-wheeled steam vehicle mounted on a horse-drawn carriage.

In 1766, British inventor James Watt improved the steam engine.

In 1769, French engineer Nicholas Cugnot built a three-wheeled steam vehicle in the Bois de Vincennes Park in Paris.

In 1801, French chemist Philips Lebon successfully developed a two-stroke engine using coal gas and hydrogen as fuel.

In 1876, German engineer Nikolous Otto invented the four-stroke engine. Also called Otto cycle.

In 1885, German engineer Carl Benz created a gasoline engine device in Mannheim. The three-wheeled vehicle mounted on a horse-drawn carriage had a 0.85-horsepower gasoline engine.

On January 29, 1886, Carl Benz obtained the world’s first automobile engine patent[1]. In July of the same year, the world's first four-wheeled vehicle was officially sold.

In 1888, French bicycle businessman Emile Roger obtained a license from Benz and began producing commercial cars.