The b450 will need an old CPU to update the motherboard beforehand. However, the MSI b450 Tomahawk among other MSI boards support MSI Flashback, which means you can update the BIOS without the need for an older CPU.
Yes you definitely need a BIOS update (and install the newest chipset drivers) BEFORE you install a 3000 Series CPU on an Asus ROG Strix B450-F MB.
The newest BIOS is 2406 (ans as far as I know is supposed to support the new 3000 series CPU's).
I personally would wait a few months at least before updating just to be sure the bugs are worked out of the BIOS updates before upgrading to a 3000 series CPU.
The b450 will need an old CPU to update the motherboard beforehand. However, the MSI b450 Tomahawk among other MSI boards support MSI Flashback, which means you can update the BIOS without the need for an older CPU.
^ That's true but,
SPECOPS70 already has a Ryzen 5 2600x on an ASUS ROG Strix B450-F Gaming.
So he will just need to update his chipset drivers and BIOS with his existing setup then he will be able to upgrade to a 3000 series CPU.