Lisa Larkin,
First I made a full backup of my system drive to an external USB drive (Seagate Backup Plus). Then I created "Acronis Rescue Media" on a thumb drive from my backup software, Acronis True Image 2021. Not real straight forward. It took a little doing to create the media with bootable WinPE recovery media and the True Image backup / restore software on it as well to a USB thumb drive. (Other apps like Partition Magic might make this process easier).
Next I went into the BIOS and set USB at the top of the EUFI boot order. (NOTE: My SYS drive was set to GPT EUFI boot, not MBR format.) Powered down, disconnected the power and data cables from the existing SYS HD and installed the SSD. I installed a 2TB Samsung 970 Plus NVMe M.2 PCIe3 x 4 SSD using a PCIe 3 x16 adapter card rather than a SATA SSD (mostly for speed). The hardware install was a piece of cake.
I unplugged the Seagate drive, plugged the (bootable) Rescue Media thumb drive into a USB slot, powered up and it booted to a WinRE window, then started True Image backup/restore application. At that point I plugged in the external Seagate USB drive with the full SYS drive backup and restored it (with all the partitions (EFI, C:Windows, Recovery Image partition ...) to the SSD. Then I powered down, unplugged the rescue media and Seagate drives, powered back up and used the function key during the boot process to access the BIOS to set PCIe to the top of the EUFI boot order and restarted. It all booted up fine, and I tested for a few days to make sure all my apps and docs etc were operating / accessible as expected. I used Disk Manager to make sure my drive letters for my internal SATA and external eSATA RAIDs and optical drive were the same as before, and that C: was assigned to the "Windows" partition of the SSD.
Then I double-checked that SATA was not first in the BIOS boot order (PCIe was first as set before). With the machine powered down, I reconnected the old SYS drive and powered back up again double checking that I had booted from the SSD and that the old SYS drive had a letter other than C. It turns out that I needed to use the command line utility, "DiskPart" to delete the EFI, recovery and another small reserved partition on the old SYS HD before I could use Disk Manager to format it. (I just formatted it as one 2 TB volume and set the letter low in the alphabet.) I created "Documents", "Pictures", "Music" and "Videos" folders on the reformatted HD to serve as targets for the move operations. After that I simply used the File Explorer->This PC->Documents->Properties Location tab to move "Documents" (repeated for "Music", "Pictures ...) to the reformatted HD. With rare exception the installed applications had no problem redirecting themselves to the moved docs/content locations.