On Linux root check or create a file “40_custom” under /etc/grub.d/

open this file using this command

[root@localhost ~]# gedit /etc/grub.d/40_custom


Once this file opens in Edit mode, type these continue from the last line of the file

menuentry "Windows 10" {
set root='(hd0,1)'
chainloader +1
}


Save this file and type this command to update grub loadder

[root@localhost ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
or
[root@localhost ~]# grub2-mkconfig >/boot/grub2/grub.cfg


and finally Reboot and Yeah you will see the Windows 10 to select it.

🙂