Using KC with ADFS

If we using KeyCloak , can we customize the default AD FS page or not? I mean to use the KC login page instead of the AD FS default Login page and keep using the AD FS for the login using the custom page?

In Keycloak you would not customize AD FS page - but if it makes sense to use Keycloak as an authentication facade, not only because of the theme - for instance, so that your client apps can use SAML and OpenID settings - you can try setting a Federation with AD (you can find some links for that).