Migrating my main drive to a thumb drive, so I can swap my SSD.

I bought a new ssd for my computer with more storage, with it I also bought a thumb drive as big as my current ssd to migrate the files from old to new. I only have the one ssd slot on my motherboard so I believe i have to go through the thumbdrive. Is it as easy as copying the drive contents of my main disk onto the thumbdrive, installing the new ssd, then moving the files from the thumbdrive to the new ssd? I also installed the Diskgenius software to clone and migrate the files. Will my computer boot normally with the OS on a thumbdrive so I can then move it? Should I just move the OS onto the thumbdrive then reinstall all my other files manually when i move it to the new ssd? thanks in advance.