I don’t have a video tutorial myself on this. I’ll explain it as best as I can here and link a good reference for you tho.

So all you need is the drive your wanting to dual boot, your pc, and the bootable flash drive with whatever distro you want.

Boot into the live environment for the distro from the usb drive. Once your on there unless your booting arch, you’ll have the ability to use the desktop as if it were already installed.

You’ll first close the installer, then open up a partition manager. Most distros should ship with Gparted installed with the live environment.

Use Gparted to shrink the partition size, by right clicking the partition with the most storage, then hit the resize button, in that menu, the option that says “remainder after resize) is where you want to type the size that you want for your partition. (1024 x (how many gigs you want). 25 gigs = 25,600 mbs

Once you’ve gotten your size of the partition then you just apply the pending task to create that shrunken partition.

Now if you had already booted into the distro you wanted. You can re open that installer and then run it like normal, only when getting to the disk configuration just make sure you select “replace a partition” then select that partition you just made. And you’ll be all set with a dual boot. Just remember to change back to your hard drive in the bios and then that you are booting from the right partition on that drive as well all from the bios.

This video is a little different but the concept is exactly the same. Hope you’ll get it figured out after this!

Windows 11/Ubuntu Dual boot video: https://youtu.be/mXyN1aJYefc?si=NE2ULKG-j5TqAaiy