Once the Fedora 34 repo is added, this might work going forward:
sudo dnf update --exclude=kernel*,kernel-*
sudo dnf repository-packages fedora-34 update
The first one does rawhide updates while excluding kernels. The second
will install newer fedora 34 kernels than you already have, even if
you have rawhide kernels, because the kernel is special. Your other
packages won't get f34 versions because that would be a downgrade.
I think.
--
Chris Murphy