linux-mbp can be updated with
sudo pacman -Syu, however it currently hasn't been updated for a while, so you may want to install a newer kernel that will work with OTP firmware selection.
.pkg.tar.zst files from here (you can skip the "docs" one), and run
sudo pacman -U path/to/pkg.tar.zsg path/to/other/pkg.tar.zst. This kernel already includes apple-ibridge and apple-bce so the dkms versions of those modules are optional.
You can also use releases from https://github.com/jamlam/mbp-16.1-linux-wifi or https://github.com/aunali1/linux-mbp-arch (Doesn't yet support OTP firmware selection). These won't have apple-bce and apple-ibridge included, so make sure dkms installs those modules for the new kernels if you need them (refer to the dkms guide for this).
git clone https://github.com/Redecorating/mbp-16.1-linux-wifi cd mbp-16.1-linux-wifi makepkg -si
You can instead clone the other repos mentioned under Updating Kernel. You may need to change the folder you