how to enable "extended dns error" option in bind?

I want to use "extended dns error" option on my recursive dns server. What config changes are required to enable EDE?

I am using BIND 9.16.18 as recursive server.

You can't (enable Extended DNS Error codes aka RFC 8914) in current (september 2021) versions of Bind.

See https://gitlab.isc.org/isc-projects/bind9/-/issues/1836

The feature is still being worked on, so it doesn't exist yet.

The current label on it is 9.19 so you might get that feature when that version of Bind is released, and you will then need to update your 9.16.18 version.

If you don't have a real specific constraint on Bind, other software do have it, for example nsd (see https://nlnetlabs.nl/projects/nsd/rfc-compliance/)