Throttle during transition VTOL->horizontal


could you please clarify how to set up the throttle so that it contributes to the horizontal thrust but not to increasing altitude during the VTOL phase? As far as I understand, both are controlled by the same RC input.

Is it the case that after starting transition, applying the full throttle will work only for the horizontal motor and not for the VTOL motors?

Is there an option that after initiating the transition, the full (horizontal) throttle is applied automatically?

This page describes how transition and throttle works.