External bootable of Catalinia not booting

I have cloned my drive storage from my July 2019 13 inch Macbook Pro to a external hard drive. I want to use that external hard drive and install macOS Big Sur on it to test it.

When I try to boot from the bootable copy off the hard drive it dose not boot, 

I have the drive plugged in and hit power then hold option then select the drive I want then it goes to the apple logo and the loading bar and it gets halfway through then I see the hard drive like turn off and then my mac turn off

Do you have any kext extensions installed? I just upgraded Catalina to Big Sur, I have Arch linux on the same disk and have external disk with Catalina, everything works ok, I use refind for booting. Try to reset PRAM and other stuff. Only problem is when boot to ext Catalina it screams that it does not recognise some disk, I guess it is new Big Sur installation because it did not do before. Anyway it works ok on my old Air 2013.

Don't think so

I went I try and boot to the external Catalinia drive it gets to the load bar then the hard drive turns off, and computer turns off. I booted into recovery and reinstall Catalinia on the external hard drive, and it was fine booting up from the external after I did that but after I shut down my mac and tried to boot it back up to the external hard drive it went back to shutting down the mac again.

I will try and reset the PRAM

Figured how to boot from the external hard drive had make sure it was connect to the internet

I’m trying to install it with the security startup turned off since if I have it on and don’t connect to the internet it won’t boot to the external hard drive, but if I connect to the internet booting to the external drive it boot fine

When I try and install Big Sur from booting to the external drive I get this errorThe Operation couldn’t be completed (BIErrorDomain error 8.)

Update do you think about creating a USB installer? and how would I go about doing that?

I made a Big Sur USB install and when it tried to boot to it it said it need a update, not sure what but did not work either way