After 9 years of playing, I just found out double tapping the horn in a cop car does those little siren bursts that goo “woo woo,” idk what it's called : r/gtaonline
Gta 5 how to disable sirens on a police car - YouTube
Controls for GTA V and GTA Online | GTA Wiki | Fandom
Full Blue Police Siren (+ Corona Removal) - GTA5-Mods.com