Samsung Galaxy 10+ System UI 12
I timed it, it is ever 5 minutes and it is 1 second tone that sounds for an Amber Alert or emergency tone combined with vibration - it is not the normal chime.
I restarted phone, turned off all notification settings, put it in airplane mode (it still chimed), uninstalled numerous apps, took it out of its case.
This is every 5 minutes!
This certainly sounds odd, @FLrenwench, do you have a charger connected to your S10+ when you hear this chime? Have you had a go at enabling Safe mode to see if the sound occurs? This temporarily disables third-party apps but leaves basic functions (calls, text, etc.) active to allow you to diagnose whether the issue is being caused by a third-party app. Here's a guide on enabling Safe mode: How to start my Galaxy phone or tablet in Safe Mode
I started the phone in safe mode, it did not beep in Safe Mode
I deleted any apps downloaded over the weekend and restarted the phone in normal mode.
Then installed Avast for Mobile
It is still beeping every 5 minutes (yes I timed it).
The beep is not the normal alert chime, it vibrates first then there is a short sound like the beginning of an emergency announcement, then cuts off quickly.
I just tried putting it in safe mode again - no beeps, but I have deleted any recent downloads and apps - this just started last night and it was only occasional, today it is at regular intervals of 5 minutes.