Local won’t appear on app in iPhone

[bear426]

Plan

Premium

Country

 USA

Device

iPhone 8

Operating System

iOS 12.1.3

I’ve had local files on my phone playlist before but when I switch phones recently I couldn’t get them to appear on my playlists. I’ve downloaded them onto my phone via iTunes and I’ve added them into my playlists on my PC. Both my PC and iPhone are on the same WiFi when I am doing this. The songs that I have purchased through iTunes will appear and play on my phone but the other mp3 files I have will only appear and play on my playslists on my PC. I’ve search through my playlists on my phone and it doesn’t even show the song. Anyone have any suggestions? Thanks.