Back in the '90s when we were teenagers, my sister had to get the loudest possible alarms you could find and set it up on a dresser on the far side of her bedroom.
Personally, I always set two alarms when it’s time to get up. Put the loudest, most obnoxious ringtone on you can think of, set them to repeat every 5 minutes, and offset them by a few minutes so that you’re basically getting an annoying alarm every 2 to 3 minutes. I taught this trick to my fiancee because she’s a heavy sleeper and a reluctant waker too. You can combine both tricks too if you need to.