Even if curl is installed via homebrew and not the MacOS default it does not automatically support HTTP/3 & QUIC. You will get this error message:
$ curl -vs --http3 https://quic.rocks:4433 option --http3: the installed libcurl version doesn't support this
After reading https://github.com/cloudflare/quiche/issues/319 and fiddling around with it a arrived at this solution:
$ wget https://raw.githubusercontent.com/cloudflare/homebrew-cloudflare/master/curl.rb$ brew uninstall curl$ brew install --HEAD -s curl.rb # takes a while$ curl --version curl 7.74.0-DEV$ curl -vs --http3 https://quic.rocks:4433
need to make change in curl.rb: libexec.install „scripts/mk-ca-bundle.pl“