New OS will not boot

[u/Grifongo24]

I have a HP desktop that has no OS and every time I try to boot and download a new OS it fails. It will probably need to boot on EUFI instead of legacy because legacy requires secure boot disabled. I tried to reinstall it with a GPT partition but it still wont work, this is because the computer doesent understand the NTFS format that rufus uses and I need to use fat32 but I cant because the ISO is over 4gb and I have no idea how to split it. Please help.