Note: Tested across a few different variants but no idea if this will work on not rooted devices or on custom roms. Let us know if you have any issues.
Step 1: Go to: https://www.apkmirror.com/apk/lgelec...-apk-download/
Step 2: Download and install the equalizer file.
Step 3: Reboot
Step 4: Open your settings and confirm it's been added by heading to: Settings > Sounds > Sound Quality and Effects > Equalizer
That's it. You're done. Yep it's that simple.
See attached pictures.
EDIT: I keep getting a "Network issue" error when I try and add photos. Will update from my computer in a couple mins. You should be able to handle this without the pics though. Stay tuned.