Based on how the script /usr/lib/kernel/install.d/99-grub-mkconfig.install (a script that runs on kernel installations) behaves, unless you are running in Xen Hypervisor or are on an architecture that doesn't support it, Fedora by default expects to have GRUB_ENABLE_BLSCFG set to true. This script is provided by the package grub2-common, so it's unlikely it can be removed without removing the GRUB bootloader's management system entirely.

More than likely, most customizations will work just fine with GRUB_ENABLE_BLSCFG set to true as long as you properly run grub-mkconfig (or just update-grub) after you make those changes so that they get applied to the bootloader portion of GRUB itself.

If for some reason you do absolutely need to disable BLS in order to get the customization you want, the proper way to enforce grub-mkconfig on new kernels would be to write a script in the /usr/lib/kernel/install.d/ directory titled like 98-grub-manual-mkconfig.install that would forcibly run the proper mkconfig command after kernel installation and initramfs generation.