iPhone volume unexpectedly drops to minimum

there are two different volume options. One for just games and other stuff like that and then one for phone calls, text, alarms, etc. if you go into your settings the hit “sounds & haptics” try pulling the volume bar 3/4 of the way to max. That should be loud enough. If it’s still dropping randomly maybe your iPhone case is too tight over the volume down button. Also once you have the volume set you could toggle off the “change with volume buttons” underneath the slider for the volume. It makes it so you can still adjust video volume and game volume, just not ringtone volume.