Man pages matching name grub-set-default in section 8:

grub-set-default.8.en	debian 10 / grub2-common
grub-set-default.8.en	debian 11 / grub2-common
grub-set-default.8.de	debian 11 / manpages-de
grub-set-default.8.en	debian 12 / grub-legacy
grub-set-default.8.en	debian 12 / grub2-common
grub-set-default.8.da	debian 12 / manpages-da
grub-set-default.8.de	debian 12 / manpages-de
grub-set-default.8.ja	debian 12 / manpages-ja