it depends on the phone and the player. some players will give choices either via alphabetical, genre, folders, artist, and more. there are plenty of music player apps at the app store to choose from. some free, some not so free.
I plan to buy a new phone, and one important function will
be to play mp3 files on it. I have a large number of these,
arranged in folders and subfolders. Do phones like
One+One, or a Huawai, allow me to hierarchically choose
an mp3 file, going through the folders? I ask because
I bought a cheap tablet, loaded it with about 20 Gb of
mp3 files in folders, and it presents them all, unfolded,
in alphabetic order. Specs for phones do not mention this
and I want to be sure I buy the right phone.