New Used MacBook Upgrade Sierra to High Sierra

I don’t use cloning apps any longer as they just pass the problem from one system to another!

I would pass on High Sierra and instead go directly to Mojave as its just better.

Best to create a bootable OS installer USB thumb drive following this guide: How to create a bootable macOS Mojave installer drive

But you have another issue which you may not be aware of: If you've got an old macOS install image, it will probably stop working today. You’ll want the OS image from here: How to upgrade to macOS Mojave jump to step 4.

Make a TimeMachine backup of your 2010 MacBook Pro HD or just use it connected via a SATA to USB adapter cable or just connect your 2010 system via a FireWire cable to your 2012 system after first booting it up under Target Disk Mode by starting it up using the T key

Reference: Mac startup key combinations