OnePlus
Custom Notification Sounds for Individual Apps auf OnePlus
By default, most apps on a OnePlus phone use the system notification sound. That is fine until you have several messaging or work apps firing alerts at the same time, because you cannot tell them apart by ear.
Oxygenos lets you override this per app and even per notification category inside that app. This matters because many apps split their alerts into several channels, for example chats, mentions, and system updates, and each channel can carry its own sound.
To change it, open Settings ➔ Apps & notifications ➔ See all apps ➔ choose the app you want to adjust ➔ Notifications ➔ pick the notification category ➔ Advanced ➔ Sound ➔ select the tone you want to use.
You are not limited to the pre-installed tones. If the app supports it, you can also pick an audio file stored on your phone, such as an mp3, and use it as a custom alert.
If you just want notifications to stay quiet during certain hours instead of sounding different, a Focus mode or scheduled Do Not Disturb setting is the better fix, since a custom sound alone will still play.
Keep in mind that a sound you assign to one category only affects that category. Other alert types from the same app keep whatever sound was set before.