Can I use reverse WHOIS to find all domains containing a particular TLD?

Yes, you can use the Domain Research Suite (DRS) to apply an advanced TLD filter. Once you access the reverse WHOIS tool (login required), you will need to click "Advanced search" followed by "In specific WHOIS fields" then select "Domain Name" and "Ends with" and add the string "*.org" for .org, "*.com" for .com, etc. in the text field. However, note that results are limited to 10,000 domains, so you may need to use the "Date filters" to specify a date range and narrow down your search.