Oclp boot icons

I was using ChatGPT for support with errors i was having on my MacBook Pro mid 2012 and it said that I can change the boot icons in oclp as in the ones that appear when I press alt and power the laptop but I cnat find it anywhere if it is possibly can you please tell me what Rez it will take what file type and if it will fuck up my disk in anyway because it’ll be my third time fully deleting my disk this week and I’ve had enough tbh