There's no good reliable starting point for a WHOIS client. It's more or less an "illusion" that you can use
whois without also specifying the whois server to query.
I'll refer to my answer here https://serverfault.com/a/615848/183318 for the available means of finding the proper WHOIS server for a TLD.
Only the method of querying IANA (WHOIS or http) is actually reliable but then instead ends you up with a huge blob of text that is relatively expensive to fetch and which also needs to parsed in a possibly semi-fuzzy manner.
$ whois -h whois.iana.org google | grep ^whois
Most WHOIS clients seem to instead rely on having a config file primed with the "known" TLDs and some falling back to a DNS lookup for
example.whois-servers.net (which does not have an entry for
google.whois-servers.net yet). I don't know how common it is for clients to even attempt a query for