cpu update

Let's say you want to go from a Pentium 4 Intel cpu to a dual core cpu, where would one get the bios to update?

Hi, Tried a build prior to this one, but as it wasn't optimal here is the new build i ll get my hands on: AMD R5 3600 OR 3600 X MSI B450 Tomahawk Max ATX G.Skill Ripjaws V 2x8 3200mhz MSI GTX 1660 Gaming X Crucial MX500 1TB SSD MSI Mag Forge 100M (6 fan) 80+ Bronze OR Gold semi-modular PSU...