Kagi doesn't provide it natively because of performance issues. They contributed to ublacklist to add kagi search. You can use it with regex and matching rules
> If you need advanced blocking features, such as specifying rules by match patterns (e.g., ://.example.com/*) or by regular expressions (e.g., /example\.(net|org)/), the uBlacklist browser extension includes support for Kagi Search.