Is there a way to block ALL domains and only allow those listed in the Allowlist

I'm trying to restrict access to all websites **EXCEPT** the ones I have listed in the Allowlist. NextDNS has a feature where a Top Level Domain (TLD) can be blocked, but that requires explicit selection of domains to be blocked. I'd like to block ALL domains with the exception of the ones listed in the Allowlist - how would I go about doing that?