How can I determine the owner of a domain like 00h7112288999000.site?

Due to the nature of these domains, traditional WHOIS lookups are unlikely to yield useful information. The domain is typically registered to the DDNS provider, not the end-user. You might be able to trace the IP address associated with the domain to a specific network, but identifying the individual user behind it is generally difficult without further information or cooperation from the DDNS provider.