Can anyone help me install a Custom OS on my old cell phone?

I have an old cell phone called LG Sunset™ LTE (L33L) that I want to completely degoogle. It is an old phone that I bought in 2013(?) that I want to install a Custom OS on. I know GrapheneOS will not install on these types or phones nor can LineageOS. I want to degoogle it so that I will not Android 5.0 on my phone. I know that the phone only has 8 GB at maximum. I moved on to another phone that I can use an Android phone. I want to use this one as an MP3 player and video player as opposed to an official phone. Can anyone help me with this? How can I completely degoogle my phone? Or install a Custom OS on it?