Your browser probably doesn't have an option to do this. If it did you'd find out that certain sites just don't work if you forbid RSA key exchange.

The type of site that wants SSL Labs A+ scores works fine. But your bank probably doesn't (they actively don't want ephemeral key exchange) and nor does some crumbly older HTTPS site running a stitched together Apache 1.x on an old Debian release.

To protect against this attack the server needs to refuse to try RSA key exchange OR you need to refuse RSA altogether including the safe and extremely popular authentication step.