You can't do this with the hosted login pages, but there is an issue to allow/disallow MFA on an application by application basis: https://github.com/FusionAuth/fusionauth-issues/issues/763
Currently, you can't bypass MFA, but you can do an end run around by using the Login API.
You can start multi factor with a code you provide: https://fusionauth.io/docs/v1/tech/apis/two-factor/#start-multi-factor
Then complete the login process with that known code: https://fusionauth.io/docs/v1/tech/apis/login/#complete-multi-factor-authentication .