If you are doing a research of available domains, instead of using Google ( websearch) use an specialized tool like the Domain Availability Search tools offered by domain registrars like Google Domains, GoDaddy, among others. Besides of telling you if the domain is available, some of them offer a list of similar domains so yo could have an idea of how unique is the domain that you are searching
By the other hand if you are looking existing domains, as is mentioned in another answer, then you have get a list or registered domains. Some places publish interesting lists like Wikipedia:
Looking at this lists could give you hints about other lists that might give you what you are looking for.
The above because Google (websearch) is good for indexing content but no so good for searching domains / urls as it hasn't search operators like start with and doesn't support something like regular expressions.
Google (websearch) might help you find if someone already did a similar project and maybe also to learn about the knowledge/skills required to do it but not be the source to dump all the URLs in first place because Google doesn't index all the existing domains/websites.