Do Keyboard Shortcuts (Ctrl + F1) Without Fn Key
You can set the Function Keys to say what the top row of keys is (that is, switch what Fn does for the top row of keys) in the BIOS, but you cannot (in any laptop I have seen) switch in BIOS what (say) F1 and F2 do (that is, you cannot switch them).
Almost all laptops however can control Sound and Brightness with some Function key arrangement.
You need to look at your Laptop Quick Start guide to see what that is.