i’ve had the product red model for 2/1/2 years, i can safely say that i hate this particular model.
ever since i got the phone, it would never let me listen to my music at full volume, with and without earbuds, because my hearing is so goddamn important. i got told i can turn it off- i can’t. an important part of my life is music as i have a bad case of tinnitus and y’know, thats how i drown it out. but since apple doesnt want my ass to be deaf when i borderline already am, fuck my music altogether. so most of the time i don’t use earbuds. so i usually lay my phone down and listen that way, but unfortunately, if i press a volume button or the power button, it literally cuts off all speakers’ volumes a great amount, so i really can’t enjoy anything but ambience. i never mistreated it and it was a brand new phone not even refurbished, and it always fucks/ed me over.
Easiest solution for you would be an external amplifier, they come in all sizes and price points, and let you turn up the volume as much as you want.
Can’t say that my 12 mini has the same problem though.