Dude, I’m not trying to be rude or anything. All I’m saying is that your claims aren’t consistent with apple’s specifications for both phones and their own advertising. Your anecdotal evidence for the iPhone 8 Plus’ stereo speakers being “better” than the iPhone X contradicts what Apple says about their own phones. Even most YouTube videos that have done a speaker comparison of the iPhone 8 Plus and the iPhone X say overall the iPhone X is louder and has more bass.
Yeah, in this case the X is clearly better sounding. Not just louder but louder and clear across a broader range of frequency. over the 8 Plus.
I'm sure not everyones ears are tuned the same way. Some people may have done damage to their hearing or have limited hearing in some other capacity. so every individual ear is different. but when you look at the science. looking at the 20-20k spectrum the X comes out on top.