You have two ways of using the PQ block. In the first case, the dynamic profile of the load is determined by the initial values (V0, P0, Q0), the type of load (np, nq) and the instantaneous value of voltage. But these parameters are classified as constant, and can't be described as a timeseries in this first mode of operation.
However, if you use external control of PQ, you are completely free to define the equation for (P, Q) where (np, nq) and (P0, Q0) can come in from a From Workspace block (Simulink). The challenge is that you need to construct the load as a current source where Ic_real = P (np, nq, V, P0, Q0) and Ic_imag = Q (np, nq, V, P0, Q0).
Easiest is if you can assume the voltage V is also a given timeseries or may be considered constant. Then you could use the block with external control of PQ mode making the problem manageable to start with. this is what I would recommend.
Good luck / Juan