OnePlus
Enable or Disable Increasing Alarm Volume auf OnePlus
The Increasing volume option controls how your OnePlus alarm ramps up in loudness once it starts ringing. Instead of playing the alarm tone at full volume immediately, the phone starts quiet and gradually raises the level until it reaches the volume you configured for that alarm.
This is useful if you want a gentler wake-up, but it also means the first few seconds of the alarm are much quieter than the rest. If you rely on hearing the alarm instantly - for example in a noisy room or with a short sleep window - a slow ramp-up can cause you to sleep through the early part of the ring.
To change this behavior, open the Clock app on your OnePlus phone. Go to Open the Clock app ➔ Open the Settings ➔ Enable or disable Increasing volume. Turning the toggle on activates the gradual ramp-up for your alarms; turning it off makes every alarm play at full set volume from the very first second.
If you still cannot hear your alarm reliably after adjusting this setting, check the alarm volume slider itself and confirm that Do Not Disturb or a scheduled Focus mode is not muting notifications during that time.