You can listen to the iPhone Morning Alarm Sound Effect (Annoying) on Asalh Love's SoundCloud.
Sites like ZEDGE offer various versions, including original and remixed "earrape" or loud variants. Key Characteristics of "Radar"
Frequent users often develop a "Pavlovian response" to the sound, feeling a sense of anxiety or being "triggered" even when they hear it during the day on someone else's phone.