For example, in the below url I need to extract just 'abc' and assign the extracted string to a new field name.
Try this one:
https://regex101.com/r/zYmSeB/1
It makes some assumptions, but they may be valid for your use case.
if url always ends with .com then you can try this as well...
...|rex field=URL "\.com\/(?<name>[^-]+)-"