[Darryl Ramm]

Start by ejecting/disconnect the external drive you have time machine backups on (that avoids any horrible mistakes). Connect the new Lacie drive.

Look at that drive in Disk Utility. It's probably formatted as HFS+ (Apple Extended...) On a modern systems just needing to restore to your MBP I would convert that to APFS... several reasons why that I'll spare you.

In Disk utility, *before* you use the drive.

Select the External Drive (BE VERY CAREFUL NOT TO SELECT THE INTERNAL DRIVE) > Click Erase > from the drop-down menu button select "APFS"

Click Apply

Then just run CCC. Create a new task in CCC with source your internal drive usually "Macintosh HD" and Destination the new external Lacie. Leave "Copy All Files" selected and "SafteyNet On" (for best safety with future incremental backups)

When CCC finishes, reboot your mac, holding down the option key while it is rebooting and choose to boot off that external drive. Check it boots and everything works. Shutdown the Mac, unplug the external drive, put it somewhere safe.

If you need to do this or not, that's up to you. I would so you have a separate boot backup outside of Timemachine. If you need to recover this will be much faster, and it's a good thing to be doing in general.

If you have a specific question on how to do something with CCC then ask, it's too much to go though how to use the whole thing, and CCC bombards you with more excessive popup help than you will likely want or need.