I have a 27" iMac late 2012 software is macOS Catalina. I purchased a Samsung T5 SSD portable drive to clone my iMac internal drive.
When selecting the Samsung SSD on the iMac and select erase to format it doesn't have the AFPS in the format pull down.
there are three other options
MAC OS EXTENDED(Journaled)
MAC OS EXTENSION (Case sensitive journalised)
I have tried each one but it doesn't recognise it when I try and clone in Carbon Copy app.
Any help would be appreciated.
I just cloned a T5 to boot my very slow iMac Late 2015 from.
In disk Utility > View > Show All Devices.
The instructions to Erase and format the T5 was : MAC OS EXTENDED(Journaled) > Guild Partition Map
After format the T5 SSD shows as APFS Volume . APFS
My iMac is now like lightning
Hopefully this is what you needed.