What is the ruling of Islamic law on using car horns loudly when escorting the bride in wedding processions?

The basic principle is the permissibility of every legitimate means that leads to the declaration and publicizing of the marriage, based on the Prophet's (peace be upon him) saying: "Announce the marriage, perform it in masjids, and beat drums over it." Islam has endorsed people's customs as long as they do not contradict the Sharia (definition), such as the mixing of men and women or the bride appearing immodestly before non-mahram (definition) men. As for expressing joy without extravagance through the aforementioned methods, there is no harm in it.