If you have 2 separate drives each with their own boot loader and you tell your bios to boot from the grub bootloader and grub has successfully detected another OS like windows everything will be fine.

The trouble with dual booting comes from splitting a drive into partitions with different OS’s on them sharing the same boot partition. Eventually windows will nuke grub and you will loose the ability to boot linux till you use a live USB to repair through chroot and fixing/installing grub manually or using a grub-repair live USB. Usually only gets complicated if you have luks set up.

I don’t advise dual booting on a single drive. I intentionally buy gaming laptops with dual drive setups and keep the windows drive untouched till the warranty is out. Just in case i have to send it in for repair. Been doing this since 2004 without ever having any bootloader issues that I didn’t cause myself.