weird flex, but okay. you must be lost.
I would absolutely not recommend a phone for an mp3 player. typically the amps in them don't particularly drive properly. they are made for yacking with your friends over the phone. playing mp3 is an add on.
I do not have a oneplus, I choose to have "unbranded" phone and buy the google pixel mainly because of the lack of disgusting shovelware companies like oneplus and samsung put on their phones. The pixel also gets first round OS updates without having to go through the third party to have them insert their shovelware into.
if you are LEGIT looking for an ACTUAL mp3 player that is phone-ish? buy a Fiio M15. got bluetooth 5, HD DAC, and can take a 300ohm headphone load like the sennheiser hd800 like nothin'
not that that's what you are here for, but anyways.