I have a early 2013 mac pro laptop and I need to upgrade from Catalina to big sur is that possible

sorry, NO. Catalina is that last MacOS for the early 2013 models.

They feature the Intel 4000 graphics and on the 15-in dual-graphics models, the GT650M. Those are considered too old to be supported by Big Sur.

What if I initiated the upgrade to Big Sur before seeing this comment above, and now my MacBook Pro is stuck in a loop of restarting itself over and over again? How do I stop the upgrade too Big Sur and revert back to Sierra or Catalina?

shut down your Mac.

at startup, hold the Option key.

Select your regular disk as the startup drive.

you should be fine now.