Apologies for the late reply.
The SimRF phase shift block applies a rotation to the carrier frequency. For example, if you a have a real modulated signal applied to a non-zero center frequency, the phase shift block will rotate the signal and make it purely imaginary.
If you need to apply a phase rotation to the baseband signal you might want to use the phase/frequency offset block from Communications System Toolbox.
If your goal is instead to apply a phase rotation to both the envelope and the carrier, then you need to use both blocks. If you want to model a time-domain delay, you need to apply a time-domain delay to the envelope and an equivalent phase rotation to the carrier. I attached an example hoping that will help in answering your question.
With best regards,