This has almost certainly been discussed before, but trying to find the simple answer (or I hope it's simple) I'm looking for has proven to be a challenge.
On earlier versions of Windows, when I wanted or needed to change out the HDD that is the boot device, usually for a larger HDD, all I would do was clone the existing HDD to the new one, use a partition manager to extend the new HDD space or create a new logical drive on that physical HDD, then "plug n' play" with that new drive. I would imagine the same thing is possible if you're going for a smaller SSD and what's currently on the HDD does not exceed the capacity of the SSD. It's been so long since I've cloned a disc that I don't know whether "clone with shrink" is even allowed.
However, I do not know whether either technique would work under Windows 10. Is it possible to do either of the above?